Bearing assemblies and apparatuses including tilting superhard bearing elements, and motor assemblies using the same

ABSTRACT

Embodiments relate to tilting superhard bearing element bearing assemblies and apparatuses. The disclosed assemblies/apparatuses may be employed in downhole motors of a subterranean drilling system or other mechanical systems. In an embodiment, a bearing assembly may include a support ring and a plurality of superhard bearing elements each of which is tilted and/or tiltably secured relative to the support ring and distributed circumferentially about an axis. Each of the superhard bearing elements includes a bearing surface and a base portion. The base portion of the at least one of the superhard bearing elements may include a tilting feature configured to allow the at least one of the superhard bearing elements to be tiltable about a tilt axis. The bearing assembly includes retaining features that secure the superhard bearing elements to the support ring.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/134,841 filed on 19 Dec. 2013, which is a continuation of U.S.application Ser. No. 13/550,831 filed on 17 Jul. 2012 (now U.S. Pat. No.8,651,743 issued on 18 Feb. 2014), which is a continuation-in-part ofU.S. application Ser. No. 13/089,725 filed on 19 Apr. 2011 (now U.S.Pat. No. 8,545,103 issued on 1 Oct. 2013), the disclosure of each of theforegoing applications is incorporated herein, in its entirety, by thisreference.

BACKGROUND

Wear-resistant, superhard compacts are utilized in a variety ofmechanical applications. For example, polycrystalline diamond compacts(“PDCs”) are used in drilling tools (e.g., cutting elements, gagetrimmers, etc.), machining equipment, bearing apparatuses, wire-drawingmachinery, and in other mechanical apparatuses.

PDCs have found particular utility as superhard bearing elements infixed-position thrust bearings within subterranean drilling systems. APDC bearing element typically includes a superhard diamond layercommonly referred to as a diamond table. The diamond table is formed andbonded to a substrate using a high-pressure/high-temperature (“HPHT”)process.

A fixed-position thrust-bearing apparatus includes a number of PDCbearing elements affixed to a support ring. The PDC bearing elementsbear against PDC bearing elements of an adjacent bearing assembly duringuse. PDC bearing elements are typically brazed directly into a preformedrecess formed in a support ring of a fixed-position thrust bearing.

SUMMARY

Embodiments of the invention relate to bearing assemblies andapparatuses that utilize individual superhard bearing elements astilting bearing elements. The disclosed bearing assemblies andapparatuses may be employed in bearing apparatuses for use in downholemotors of a subterranean drilling system or other mechanical systems.

In an embodiment, a bearing assembly may include a support ring and aplurality of superhard bearing elements each of which is tilted and/ortiltably secured relative to the support ring and distributedcircumferentially about an axis. Each of the superhard bearing elementsmay include a bearing surface and a base portion. The base portion of atleast one of the superhard bearing elements may include a tiltingfeature configured to allow the at least one of the superhard bearingelements to be tiltable about a tilt axis. The bearing assembly includesa plurality of retaining features that secure the superhard bearingelements to the support ring such that the superhard bearing elementsare tilted and/or tiltably secured to the support ring. In anembodiment, the tilting feature may include a pivot, such as a generallyhemispherical or rocker pivot.

In another embodiment, a bearing apparatus includes a rotor and astator. The rotor or stator may include any of the bearing assemblyembodiments disclosed herein.

Other embodiments are directed to motor assemblies including any of thebearing assembly and apparatus embodiments disclosed herein.

Features from any of the disclosed embodiments may be used incombination with one another, without limitation. In addition, otherfeatures and advantages of the present disclosure will become apparentto those of ordinary skill in the art through consideration of thefollowing detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate several embodiments of the present disclosure,wherein identical reference numerals refer to identical or similarelements or features in different views or embodiments shown in thedrawings.

FIG. 1A is an isometric view of a hydrodynamic tilting padthrust-bearing assembly according to an embodiment.

FIG. 1B is an isometric partial cross-sectional view taken along line1B-1B of the hydrodynamic tilting pad thrust-bearing assembly shown inFIG. 1A.

FIG. 1C is an isometric view of one of the tilting pads shown in FIGS.1A and 1B, the tilting pad being segmented into multiple segments havingsubstantially planar adjoining ends according to an embodiment.

FIG. 1D is a cross-sectional view taken along line 1D-1D of the bearingtilting pad shown in FIG. 1C.

FIG. 2A is an isometric view of three adjacent superhard bearingsegments of a tilting pad, the superhard bearing segments having slottedends forming a set of seams between the three depicted superhard bearingsegments according to an embodiment.

FIG. 2B is a top plan view of the tilting pad of FIG. 2A, the tiltingpad being fully assembled and including six superhard bearing segmentsdefining seams therebetween.

FIG. 3 is a top plan view of a tilting pad comprising multiple segmentshaving serrated ends that form seams between the multiple segmentsaccording to another embodiment.

FIG. 4 is an isometric view of a tilting pad comprising a unitarysuperhard bearing element according to another embodiment.

FIG. 5A is an isometric cutaway view of a hydrodynamic tilting padthrust-bearing apparatus that may employ any of the disclosedhydrodynamic tilting pad thrust-bearing assemblies according to anembodiment, with a housing thereof shown in cross-section.

FIG. 5B is an isometric cross-sectional view of the hydrodynamic tiltingpad thrust-bearing apparatus taken along line 5B-5B of FIG. 5A showing afluid film that develops between tilting pads of a stator and asubstantially continuous superhard bearing element of a rotor.

FIG. 6A is an isometric view of a runner of a hydrodynamic tilting padthrust-bearing assembly according to one embodiment.

FIG. 6B is an isometric partial cross-sectional view taken along theline 6B-6B of FIG. 6A.

FIG. 7A is an exploded isometric view of a hydrodynamic tilting padradial bearing apparatus that may use teachings of any of the disclosedhydrodynamic tilting pad thrust-bearing assemblies according to anembodiment.

FIG. 7B is an isometric partial cross-sectional view of radial tiltingpad stator of the hydrodynamic tilting pad radial bearing apparatus ofFIG. 7A according to an embodiment.

FIG. 7C is an isometric partial cross-sectional view of a rotor of thehydrodynamic tilting pad radial bearing apparatus of FIG. 7A accordingto an embodiment.

FIG. 8A is an isometric view of a thrust-bearing assembly according toan embodiment.

FIG. 8B is a top plan view of the thrust-bearing assembly shown in FIG.8A.

FIG. 8C is an isometric partial cross-sectional view taken along line8C-8C of the thrust-bearing assembly shown in FIG. 8A.

FIG. 8D is an isometric view of one of the tilting bearing elementsshown in FIG. 8A according to an embodiment.

FIG. 8E is a cross-sectional view taken along line 8E-8E of the tiltingbearing element shown in FIG. 8D.

FIG. 8F is a bottom plan view of the titling bearing element shown inFIG. 8D.

FIG. 9A is an isometric view of a thrust-bearing assembly according toanother embodiment.

FIG. 9B is a top plan view of the thrust-bearing assembly shown in FIG.9A.

FIG. 9C is a partial cross-sectional view taken along line 9C-9C of thethrust-bearing assembly shown in FIG. 9A.

FIG. 9D is a top partial plan view of the support ring shown in FIG. 9A.

FIG. 9E is an isometric view of one of the tilting bearing elementsshown in FIG. 9A according to an embodiment.

FIG. 9F is a cross-sectional view taken along line 9F-9F of the tiltingbearing element shown in FIG. 9E.

FIG. 10A is an isometric view of a tilting bearing element according toanother embodiment.

FIG. 10B is a cross-sectional view taken along line 10B-10B of thetilting bearing element shown in FIG. 10A.

FIG. 11A is an isometric cutaway view of a thrust-bearing apparatus thatmay employ any of the disclosed thrust-bearing assemblies according toanother embodiment.

FIG. 11B is an isometric cross-sectional view of the thrust-bearingapparatus taken along line 11B-11B of FIG. 11A according to anembodiment.

FIG. 12A is an isometric exploded view of a radial bearing apparatusaccording to another embodiment.

FIG. 12B is an isometric partial cross-sectional view of a stator of theradial bearing apparatus of FIG. 12A according to an embodiment.

FIG. 12C is an isometric partial cross-sectional view of a rotor of theradial bearing apparatus of FIG. 12A according to an embodiment.

FIG. 13 is a schematic isometric cutaway view of a subterranean drillingsystem including one of the disclosed thrust-bearing apparatusesaccording to another embodiment.

DETAILED DESCRIPTION

Embodiments of the invention relate to bearing assemblies andapparatuses that utilize individual superhard bearing elements astilting bearing elements, which may be operated hydrodynamically. Thedisclosed tilting pad bearing assemblies and apparatuses may be employedin downhole motors of a subterranean drilling system or other mechanicalsystems. Motor assemblies including at least one of such bearingassemblies or apparatus are also disclosed, as well as methods offabricating such bearing assemblies and apparatuses utilizing superhardcompacts.

While the description herein provides examples relative to asubterranean drilling and motor assembly, the tilting pad bearingassembly and apparatus embodiments disclosed herein may be used in anynumber of applications. For instance, tilting pad bearing assemblies andapparatuses may be used in pumps, motors, compressors, turbines,generators, gearboxes, and other systems and apparatuses, or in anycombination of the foregoing. Furthermore, while the embodimentsdisclosed herein are described as being operated hydrodynamically, thetilting pad bearing assemblies and apparatuses may also be operatedpartially hydrodynamically or not hydrodynamically, if desired orneeded.

FIGS. 1A and 1B are isometric and isometric partial cross-sectionalviews, respectively, of a hydrodynamic tilting pad thrust-bearingassembly 100 according to an embodiment. The bearing assembly 100includes a support ring 102 that carries a plurality ofcircumferentially-spaced tilting pads 104. The tilting pads 104 mayinclude, for instance, fixed tilting pads, adjustable tilting pads,self-establishing tilting pads, other bearing pads or elements, orcombinations of the foregoing.

The tilting pads 104 of the illustrated embodiment generally have atruncated pie-shaped geometry or a generally trapezoidal geometry, andmay be distributed about a thrust axis 106, along which a thrust forcemay be generally directed during use. Each tilting pad 104 may belocated circumferentially adjacent to another tilting pad 104, with agap 108 or other offset therebetween. For instance, the gap 108 mayseparate adjacent tilting pads 104 by a distance of about 2.0 mm toabout 20.0 mm, or more particularly a distance of about 3.5 mm to about15 mm, although the separation distance may be greater or smaller. Forinstance, as the size of the hydrodynamic tilting pad bearing assembly100 increases, the size of the tilting pads 104 and/or the size of thegaps 108 may also increase. Each tilting pad 104 includes a discretesuperhard bearing surface 116, such that the tilting pads 104collectively provide a non-continuous superhard bearing surface. Theterm “superhard,” as used herein, means a material having a hardness atleast equal to a hardness of tungsten carbide.

To support the tilting pads 104 of the bearing assembly 100, the supportring 102 may define a channel 110 and the tilting pads 104 may be placedwithin the channel 110. In other embodiments, the support ring 102 maydefine multiple pockets or otherwise define locations for the tiltingpads 104. The tilting pads 104 may then be supported or secured withinthe support ring 102 in any suitable manner. For instance, as discussedhereafter, a pivotal connection may be used to secure the tilting pads104 within the support ring 102, although any other suitable securementor attachment mechanism may also be utilized. The support ring 102 mayalso include an inner, peripheral surface defining an aperture 114. Theaperture 114 may be generally centered about the thrust axis 106, andmay be adapted to receive a shaft (e.g., a downhole drilling motorshaft).

As best shown in FIG. 1B, each tilting pad 104 may include a pluralityof superhard bearing segments having a plurality of materials, layers,segments, or other elements, or any combination of the foregoing. Forinstance, as discussed in greater detail herein, the tilting pads 104may be composed of multiple superhard bearing segments. In such anembodiment, multiple individual segments may be arranged relative toeach other to collectively define a hydrodynamic superhard bearingsurface 116 for each tilting pad 104.

Each tilting pad 104 optionally includes multiple layers or othercomponents. For instance, each segment of the tilting pad 104 may be asuperhard compact that includes a superhard table 118 bonded to asubstrate 120. The superhard table 118 may be at least partially madefrom a number of different superhard materials. Suitable materials foruse in the superhard table 118 include natural diamond, sintered PCD,polycrystalline cubic boron nitride, diamond grains bonded together withsilicon carbide, or combinations of the foregoing. In an embodiment, thesuperhard table 118 is a PCD table that includes a plurality of directlybonded-together diamond grains exhibiting diamond-to-diamond bondingtherebetween (e.g., sp³ bonding), which define a plurality ofinterstitial regions. A portion of, or substantially all of, theinterstitial regions of such a superhard table 118 may include ametal-solvent catalyst or a metallic infiltrant disposed therein that isinfiltrated from the substrate 120 or from another source. For example,the metal-solvent catalyst or metallic infiltrant may be selected fromiron, nickel, cobalt, and alloys of the foregoing. The superhard table118 may further include thermally-stable diamond in which themetal-solvent catalyst or metallic infiltrant has been partially orsubstantially completely depleted from a selected surface or volume ofthe superhard table 118 using, for example, an acid leaching process.

For example, appropriately configured PDCs may be used as the tiltingpads 104, which may be formed in an HPHT processes. For example, diamondparticles may be disposed adjacent to the substrate 120, and subjectedto an HPHT process to sinter the diamond particles to form a PCD tablethat bonds to the substrate thereby forming the PDC. The temperature ofthe HPHT process may be at least about 1000° C. (e.g., about 1200° C. toabout 1600° C.) and the cell pressure of the HPHT process may be atleast 4.0 GPa (e.g., about 5.0 GPa to about 12 GPa or about 7.5 GPa toabout 11 GPa) for a time sufficient to sinter the diamond particles.

The diamond particles may exhibit an average particle size of about 50μm or less, such as about 30 μm or less, about 20 μm or less, about 10μm to about 18 μm, or about 15 μm to about 18 μm. In some embodiments,the average particle size of the diamond particles may be about 10 μm orless, such as about 2 μm to about 5 μm or submicron. In someembodiments, the diamond particles may comprise a relatively larger sizeand at least one relatively smaller size. As used herein, the phrases“relatively larger” and “relatively smaller” refer to particle sizes (byany suitable method) that differ by at least a factor of two (e.g., 30μm and 15 μm). According to various embodiments, the mass of diamondparticles may include a portion exhibiting a relatively larger size(e.g., 30 μm, 20 μm, 15 μm, 12 μm, 10 μm, 8 μm) and another portionexhibiting at least one relatively smaller size (e.g., 6 μm, 5 μm, 4 μm,3 μm, 2 μm, 1 μm, 0.5 μm, less than 0.5 μm, 0.1 μm, less than 0.1 μm).In one embodiment, the diamond particles may include a portionexhibiting a relatively larger size between about 10 μm and about 40 μmand another portion exhibiting a relatively smaller size between about 1μm and 4 μm. In some embodiments, the diamond particles may comprisethree or more different sizes (e.g., one relatively larger size and twoor more relatively smaller sizes), without limitation. The PCD tableso-formed after sintering may exhibit an average diamond grain size thatis the same or similar to any of the foregoing diamond particle sizesand distributions.

In some embodiments, one or more sp²-carbon-containing additives may bemixed with the diamond particles. For example, the one or moresp²-carbon-containing additives may be present in a mixture with thediamond particles in an amount of about 1 weight percent (“wt %”) toabout 15 wt %, such as 3 wt % to about 12 wt %, about 4.5 wt % to about6.5 wt %, about 4.5 wt % to about 5.5 wt, or about 5 wt % of themixture. The one or more sp²-carbon-containing additives may be chosenfrom graphite, graphene, fullerenes, ultra-dispersed diamond particles,or combinations of the foregoing.

In an embodiment, the superhard table 118 may be integrally formed withthe substrate 120. For example, the superhard table 118 may be asintered PCD table that is integrally formed with the substrate 120. Insuch an embodiment, the infiltrated metal-solvent catalyst may be usedto catalyze formation of diamond-to-diamond bonding between diamondgrains of the superhard table 118 from diamond powder during HPHTprocessing. In another embodiment, the superhard table 118 may be apre-sintered superhard table that has been HPHT bonded to the substrate120 in a second HPHT process after being initially formed in a firstHPHT process. For example, the superhard table 118 may be a pre-sinteredPCD table that has been leached to substantially completely removemetal-solvent catalyst used in the manufacture thereof and subsequentlyHPHT bonded or brazed to the substrate 120 in a separate process.

In some embodiments, the superhard table 118 may be leached to deplete ametal-solvent catalyst or a metallic infiltrant therefrom in order toenhance the thermal stability of the superhard table 118. For example,where the superhard table 118 is a PCD table, the superhard table 118may be leached to remove at least a portion of the metal-solventcatalyst from a working region thereof to a selected depth that was usedto initially sinter the diamond grains to form a leachedthermally-stable region. The leached thermally-stable region may extendinwardly from the superhard bearing surface 116 to a selected depth. Inone example, the depth of the thermally-stable region may be about 10 μmto about 500 μm. More specifically, in some embodiments, the selecteddepth is about 50 μm to about 100 μm or about 200 μm to about 350 μm.The leaching may be performed in a suitable acid, such as aqua regia,nitric acid, hydrofluoric acid, or mixtures of the foregoing.

The substrate 120 may similarly be formed from any number of differentmaterials, and may be integrally formed with, or otherwise bonded orconnected to, the superhard table 118. Materials suitable for thesubstrate 120 may include, without limitation, cemented carbides, suchas tungsten carbide, titanium carbide, chromium carbide, niobiumcarbide, tantalum carbide, vanadium carbide, or combinations thereofcemented with iron, nickel, cobalt, or alloys thereof. For example, inan embodiment, the substrate 120 comprises cobalt-cemented tungstencarbide. However, in certain embodiments, the superhard tables 118 maybe omitted, and each superhard bearing segment may be made from asuperhard material, such as cemented tungsten carbide. In otherembodiments, the substrate 120 may be omitted and the superhard bearingsegment may be a superhard material, such as a polycrystalline diamondbody that has been leached to deplete metal-solvent catalyst therefromor may be an un-leached PCD body.

In the embodiment illustrated in FIGS. 1A and 1B, the superhard tables118 of mating superhard bearing segments may collectively define asubstantially continuous superhard bearing surface 116 of a respectivetilting pad 104. More particularly, the tilting pads 104 may be used inconnection with a runner or other superhard bearing element. In general,the hydrodynamic tilting pad bearing assembly 100 may rotate relative toa runner or other superhard bearing element while a lubricant or otherfluid floods the hydrodynamic tilting pad bearing assembly 100 and therunner. As the bearing assembly 100 is rotated relative to a runner, afluid film separating the runner from the superhard bearing surfaces 116may develop. For favorable use of the hydrodynamic forces within thelubricant, the tilting pads 104 may tilt which may result in a higherlubricant film thickness existing at a leading edge (i.e., an edge of atilting pad 104 that would be traversed first by any line on the runnerwhile the assembly 100 moves in the direction of rotation of theassembly 100), than at a trailing edge (i.e., an edge of a tilting pad104 over which a line of the superhard bearing element is second to passin the direction of rotation of the assembly 100), at which a minimumfilm thickness may develop.

In the illustrated embodiment, the set of superhard bearing segmentscollectively defining at least a portion of the tilting pad 104 aresecured to a support plate 122. The support plate 122 may, for instance,be formed of a metal, an alloy, a cemented carbide material, othermaterial, or any combination thereof. The substrate 120 of the superhardbearing segments may be secured to the support plate 122 by brazing,welding, or other method. In some embodiments, the support plate 122 maydefine a pocket into which the superhard bearing segments may beassembled and/or positioned. In at least one embodiment, the supportplate 122 has an integral construction such that a single segment mayform substantially the full support plate 122, while multiple superhardbearing segments may be used to form the superhard bearing surface 116.In other embodiments, multiple segments of one or more materials may beused to form or define the support plate 122.

The degree to which the tilting pads 104 rotate or tilt may be varied inany suitable manner. For instance, in an embodiment, the tilting pads104 may be tilted about respective radial axes that extend radially fromthe thrust axis 106 and through each respective tilting pad 104. In FIG.1B, the support plate 122 may be attached to a pin 124. The pin 124 maybe allowed to at least partially rotate, or may otherwise define orcorrespond to a tilt axis 125. For instance, in accordance with someembodiments, the pin 124 is journaled or otherwise secured within thesupport ring 102 in a manner that allows the pin 124 to rotate relativeto the support ring 102. The pin 124 may be fixed to the support plate122 such that as the pin 124 rotates relative to the support ring 102,the support plate 122 may also rotate or tilt relative to the axis 125of the pin 124. The pin 124 and support plate 122 may rotate or tiltbetween zero and twenty degrees in some embodiments, such that thesuperhard bearing surfaces 116 of the respective tilting pads 104 mayalso tilt between about zero and about twenty degrees relative to thepin 124 or other horizontal axis. In other embodiments, the pin 124and/or the superhard bearing surface 116 may rotate between about zeroand about fifteen degrees, such as a positive or negative angle (A) ofabout 0.5 to about 3 degrees (e.g., about 0.5 to about 1 degree or lessthan 1 degree) relative to the axis 125 of the pin 124. In some cases,the support ring 102 may be configured for bidirectional rotation. Insuch a case, the pin 124 may be allowed to rotate in clockwise andcounterclockwise directions. In such an embodiment, the superhardbearing surface 116 may thus tilt in either direction relative to theaxis of the pin 124 and/or the support ring 102. For instance, thesuperhard bearing surface 116 may be rotated to a position anywherebetween a positive or negative angle of about twenty degrees relative toan axis of the pin 124, such as a positive or negative angle (A) ofabout 0.5 to about 3 degrees (e.g., about 0.5 to about 1 degree or lessthan 1 degree) relative to the axis 125 of the pin 124.

The pin 124 may be used to allow the tilting pads 104 to selectivelyrotate. For instance, the tilting pads 104 may be self-establishing suchthat based on the lubricant used, the axial forces applied along thethrust axis, the rotational speed of the runner or hydrodynamic tiltingpad bearing assembly 100, other factors, or combinations of theforegoing, the tilting pads 104 may automatically or otherwise adjust toa desired tilt or other orientation. In still other embodiments, thetilting pads 104 may be fixed at a particular tilt, or may be manuallyset to a particular tilt with or without being self-establishing.

Further, the pin 124 represents a single mechanism for facilitatingrotation, translation, or other positioning of the tilting pads 104 soas to provide tilting pad superhard bearing surfaces 116. In otherembodiments, other mechanisms may be used. By way of illustration,leveling links, pivotal rockers, spherical pivots, other elements, orany combination of the foregoing may also be used to facilitatepositioning of the tilting pads 104 in a tilted configuration. In anembodiment, the support plate 122 may be used to facilitate rotation ofa respective tilting pad 104. The support plate 122 may, for instance,be machined or otherwise formed to include a receptacle, an opening, orother structure into which the pin 124 may be at least partiallyreceived or secured. In embodiments in which the pin 124 is excluded,the support plate 122 may be machined or otherwise formed to includeother components, such as spherical pivot, pivotal rocker, or levelinglink interface. The support plate 122 may be formed of any suitablematerial, such as steel or other alloy; however, in some embodiments thesupport plate 122 is formed of a material that is relatively softer thanthe substrate 120, such that the support plate 122 may be relativelyeasily machined or formed into a desired shape or form. In otherembodiments, the support plate 122 can be eliminated and the substrate120 may be directly machined or formed to facilitate tilting of thetilting pad 104.

In some embodiments, the tilt axis of the tilting pads 104 is centeredrelative to the tilting pads 104. For instance, where the support ring102 may be configured for bi-directional rotation, the tilt axis of thetilting pads 104 may be centered due to either of opposing edges of thetilting pads 104 being the leading or trailing edge, based on aparticular direction of rotation. In other embodiments, the tilt axis ofa tilting pad 104 may be offset relative to a center of the tilting pads104. For instance, where the support ring 102 is part of a rotorconfigured for only unidirectional rotation, the axis of rotation of thetilting pad 104 may be offset such that the axis of rotation is closerto one of the leading edge or the trailing edge of the tilting pad 104.In other embodiments, a tilt axis may be offset from center despite arotor being configured for bidirectional rotation, or a tilt axis may becentered despite a rotor being configured for unidirectional rotation.

The use of superhard materials such as those contemplated in the presentdisclosure may provide wear resistance, frictional, or other propertiesthat extend the useful life and/or utility of the corresponding bearing,motor, or other assemblies described herein. For instance, in someapplications, hardened steel bearing tilting pads may wear at a ratethat is between five and twenty times greater than bearing pads made ofsuperhard materials. Thus, in at least some applications, use ofsuperhard materials in a tilting pad bearing assembly may significantlyincrease the potential useful life of a bearing assembly.

While superhard materials may thus provide desirable wearcharacteristics, use of some superhard materials may be limited invarious regards. For instance, certain types of superhard materials maybe manufacturable in limited quantities, or may be available withcertain size restrictions. Such limitations may be the result oftechnological, quality, or economic constraints. For instance, in somecases, the technology to produce large pieces of a superhard materialmay not exist, or developing machinery that may produce large pieces maybe cost prohibitive, or result in low quality components. PDCs are asuperhard article including at least one such material that isconsidered to have production size constraints. For instance, asdescribed herein, PDCs may be produced using an HPHT sintering and/orbonding process. To maintain the temperature and pressure requirementsover a large surface area, and thereby produce large segments of PDCs,can consume large amounts of power and require large, powerful, andsophisticated machinery. If such pressure and temperature tolerances arenot maintained, the PDCs may include defects that reduce desirable wearresistance and/or frictional characteristics of the PDCs. Moreover, thetemperature and/or pressure requirements for production of a highquality and large PDC may exceed the capabilities of currently availableHPHT presses. Consequently, PDCs are currently produced under sizerestrictions. For example, PDCs are available in limited sizes thattypically range up to about 25 mm to about 75 mm (e.g., about 25 mm toabout 30 mm) in diameter for cylindrical PDCs and up to about 3.0 mm indiamond table thickness.

Where the hydrodynamic tilting pad bearing assembly of FIGS. 1A and 1B,includes superhard bearing segments formed from PDCs or otherpolycrystalline diamond material, use of a unitary PDC for an entiremolding element may currently be available primarily where the tiltingpad 104 is very small (e.g., having size dimensions limited to a maximumdimension of about 25 mm to about 30 mm). Tilting pad bearingassemblies, however, often require or use tilting pads that far exceedthe size of a typical PDC. For instance, in a turbine application, itmay not be uncommon for tilting pad bearing assemblies to utilizetilting pads having length and/or width dimensions measuring 30 mm ormore. For instance, tilting pads may be used in bearing systems wheretilting pads measure between about 30 mm and about 1500 mm. Moreparticularly, in some embodiments, a length and/or width of a tiltingpad may measure between about 50 mm and about 1000 mm, although largeror smaller tilting pads may be utilized. Because of the significant wearresistive properties that PDCs or other superhard materials provide, itis nonetheless desirable to use superhard materials for large tiltingpads or other superhard bearing segments, even when the tilting padsexceed the size of available superhard materials.

According to some embodiments, superhard materials such aspolycrystalline diamond or PDCs including polycrystalline diamond may beformed as multiple independent superhard bearing segments that may bejoined and/or assembled together to collectively define a superhardbearing element and/or superhard bearing surface. FIGS. 1C and 1Dillustrate in greater detail such an embodiment in which multiplesegments are combined to define a superhard bearing element in the formof a tilting pad.

In particular, FIGS. 1C and 1D are isometric and cross-sectional views,respectively, of a single tilting pad 104 that may be used in connectionwith the hydrodynamic tilting pad bearing assembly described above. Thetilting pad 104 includes multiple superhard bearing segments 126 a-fthat collectively defines the bearing pad 126, including a substantiallycontinuous superhard bearing surface 116. Each superhard bearing segment126 a-f may include a superhard table 118 bonded to a substrate 120, andeach segment 126 a-f may further be secured within the support plate 122by brazing, press-fitting, fastening with fasteners, or other suitableattachment mechanism. In the illustrated embodiment, the support plate122 may facilitate attachment of the segments 126 a-f to the supportplate 122 by including an interior surface 128 that defines an interiorpocket 130. The pocket 130 may be sized to generally correspond to asize of the collective, assembled set of segments 126 a-f. The superhardbearing segments 126 a-f may be assembled within the pocket 130 andsecured to the support plate 122 by brazing the segments 126 a-f to thesupport plate 122, press-fitting the segments 126 a-f to the supportplate 122 and/or against each other, attaching each of the superhardbearing segments 126 a-f to the support plate 122 using a mechanicalfastener, or using another suitable technique, or any combination of theforegoing. It is noted that the support plate 122 merely represents oneembodiment for a support plate and other configurations may be used. Forexample, according to another embodiment, a support plate may lack apocket or other receptacle. In still another embodiment, the supportplate may be eliminated. For instance, the segments 126 a-f may bedirectly connected together and the substrates 120 may directly engagethe support ring 102 (FIGS. 1A and 1B) and/or a tilt mechanism.

The illustrated embodiment shows an example structure of the superhardbearing segments 126 a-f, and an example of how the superhard bearingsegments 126 a-f may be assembled together. In this embodiment, sixsuperhard bearing segments 126 a-f collectively define a pie-shapedbearing pad 126 and a substantially continuous superhard bearing surface116, although more or fewer than six segments may be provided.Generally, more than one bearing segment may be provided to collectivelyform a tilting pad. Each superhard bearing segment 126 a-f may includeat least one outer edge region 132 and at least one interior edge region134. In the illustrated embodiment, each outer edge region 132 defines aportion of a periphery of the superhard bearing surface 116. Eachinterior edge region 134 may be configured to correspond with, and insome embodiments may mesh with, corresponding interior edge regions ofone or more of other of the superhard bearing segments 126 a-f. In FIG.1C, for instance, each of the superhard bearing segments 126 a-f isconfigured to be arranged such that the interior edge region 134 mateswith corresponding interior edge regions of at least two and sometimesthree adjacent segments 126 a-f.

In the illustrated embodiment, the superhard bearing surface 116 issubstantially planar, although such embodiment is merely illustrative.In other embodiments, the superhard bearing surface 116 may be curved,or have another contour or topography. Moreover, the outer edges of thesuperhard bearing surface 116 optionally include a chamfer 140. Thechamfer 140 may be formed by placing a chamfer on the individual outeredge regions 132 of each of the superhard bearing segments 126 a-f. Thesuperhard bearing surface 116 may also take a number of other forms. Forinstance, in FIG. 1C, the superhard bearing surface 116 is substantiallypie shaped with a curved and chamfered outer edge 142 and curved andchamfered interior edge 144. Chamfered side edges 146, 148 may besubstantially straight and taper inward from the outer edge 142 to theinterior edge 144. In other embodiments, the edges of a superhardbearing surface 116 may define other shapes, including radiused,arcuate, circular, elliptical, trapezoidal, or other shaped surfaces, ormay form a sharp edge.

The superhard bearing segments 126 a-f may also be arranged to each haveany desired individual shape. By way of illustration, a set of seams 136may be at least partially formed between separate superhard bearingsegments 126 a-f and each superhard bearing segment 126 a-f may have adifferent size and/or shape. The superhard bearing segments 126 a-fand/or seams 136 may be non-symmetrical. In other embodiments, however,the seams 136 and/or the superhard bearing segments 126 a-f may definethe superhard bearing surface 116 in a substantially symmetricalfashion.

Any number of superhard bearing segments may be used to form a superhardbearing surface 116. For instance, as noted above, a bearing tilting padmay be sized many times larger than a largest available size of a PDC orother material used to form a portion of the bearing tilting pad, or maybe small enough to be formed of a single PDC. In FIG. 1C, six superhardbearing segments 126 a-f may be used to define the full size of thesuperhard bearing surface 116. In other embodiments, however, more orless than six superhard bearing segments may be used. By way ofillustration, a bearing tilting pad measuring 75 mm in circumferentialwidth and 100 mm in radial length, may include ten or more individualsegments. In some embodiments, some individual segments include onlyinterior edges of the corresponding superhard bearing surface, such aswhere a segment is bounded in all directions by other of the superhardbearing segments. Thus, it is not necessary that a superhard bearingsegment have a portion thereof corresponding to an outer edge of thesuperhard bearing surface 116.

The interior edge regions 134 of the superhard bearing segments 126 a-fmay be configured to limit fluid from being able to leak through theseams 136 formed between adjacent superhard bearing segments 126 a-f. Byway of illustration, the seams 136 may be interconnected and defined byinterfaces between the interior edge regions 134. Depending upon thetolerances of the superhard bearing segments 126 a-f, all or a portionof the seams 136 may comprise a relatively small gap 138. For example,the gap 138 may have a width of about 0.001 mm to about 3.5 mm, moreparticularly a width of about 0.0025 mm to about 2.5 mm, and moreparticularly a width of about 0.125 mm to about 1.25 mm. Moreparticularly still, the gap 138 may have a width from about 0.025 mm upto about 1.0 mm. In another embodiment, the gap 138 may have a widthfrom about 0.005 mm up to about 0.50 mm. As the gaps 138 decrease insize, it may become more difficult for fluid to flow radially betweenthe gaps 138 and leak from the superhard bearing surface 116 of thesuperhard bearing element 104. However, it should be noted that in atleast some operational conditions, entrained fluid in the gaps 138 mayassist with formation of a hydrodynamic film on the superhard bearingsurface 116.

The interior edge regions 134 of the superhard bearing segments 126 a-fin FIGS. 1C and 1D may be substantially straight or planar and maycreate substantially planar seams 136 between the various segments 126a-f. In other embodiments, one or more segments may exhibit otherconfigurations or geometry that depart from the illustrated embodimentin FIGS. 1A-1D. For example, FIGS. 2A and 2B illustrate isometric andtop plan views, respectively, of a tilting pad 204 according to anotherembodiment. The tilting pad 204 includes multiple superhard bearingsegments 226 a-f, each of which may include a superhard table 218 bondedto a substrate 220. The substrate 220 and/or superhard table 218 mayfurther be bonded to a support plate 222 using a brazing, fastening, orother process such as those described herein. The tilting pad 204 mayalso be configured to pivot or otherwise tilt. For instance, a pin 224may be attached to the support plate 222. The pin 224 may have a centralaxis 235 about which it tilts, thereby allowing the superhard bearingsurface 216 to also pivot, rotate, tilt, or otherwise move about thecentral axis 235.

The superhard bearing segments 226 a-f of the illustrated embodimenteach include interior edge regions 234 configured to correspond toand/or mate with interior edge regions 234 of two or three adjacentsuperhard bearing segments 226 a-f. Each of the superhard bearingsegments 226 a-f may further include an outer edge region 232 definingat least a portion of the periphery of the superhard bearing surface216. As discussed herein, the foregoing is merely an example. In otherembodiments, there may be one or more superhard bearing segments that donot include an outer edge region, include an interior edge regioncorresponding to, or mating with, only one or more than three adjacentsuperhard bearing segments, or superhard bearing segments may have stillother configurations.

In the illustrated embodiment, the superhard bearing segments 226 a-fmay include, at their respective interior edge regions 234, generallyrectangular-shaped slots 250 and rectangular-shaped ridges 252. Theslots 250 and ridges 252 may be configured to correspond to andpotentially mesh with corresponding ridges 252 and slots 250 ofadjoining segments 226 a-f. Consequently, the superhard bearing segments226 a-f may at least partially interlock along respective interior edgeregions 234.

Each superhard bearing segment 226 a-f may thus be positioned radially,circumferentially, or otherwise adjacent to another of the superhardbearing segments 226 a-f, with one of the seams 236 formed therebetween.In some embodiments, interlocked superhard bearing segments 226 a-f mayact to limit fluid leakage at the superhard bearing surface 216. Forinstance, the seams 236 may define a tortuous path to limit fluidleakage through the seams 236. If present, gaps located between adjacentsuperhard bearing segments 226 a-f may further be filled with a sealantmaterial to help limit leakage of fluid through the seams 236. Forexample, gaps between interior edge regions 234 may be substantiallyfilled with a sealant material. Examples of sealant materials mayinclude a ceramic material, metallic material, polymeric material, oranother suitable material, or any combination of the foregoing. In anembodiment, the sealant material may exhibit abrasion and/or erosionresistance to commonly used drilling fluids (also known as drillingmud). For example, a sealant material may comprisechemically-vapor-deposited (“CVD”) diamond or a CVD-deposited carbidematerial (e.g., binderless tungsten carbide). Specifically, one exampleof a commercially available CVD binderless tungsten carbide material(currently marketed under the trademark HARDIDE®) is currently availablefrom Hardide Layers Inc. of Houston, Tex.

In other embodiments, a binderless tungsten carbide material may beformed by physical vapor deposition (“PVD”), variants of PVD,high-velocity oxygen fuel (“HVOF”) thermal spray processes, supersonictransfer (“SST”), or any other suitable process, without limitation. Instill other embodiments, the braze alloy used to braze the superhardbearing segments 226 a-f to the support plate 222 may infiltrate theseams 236 and substantially fill all or a portion of the gaps at theseams 236, which may exist at the interfaces of the interior edgeregions 234 of mating superhard bearing segments 226 a-f. For example,suitable abrasion resistant braze alloys include, but are not limitedto, silver-copper based braze alloys commercially known as braze 505 andbraze 516 and are available from Handy & Harmon of Canada Limited. Inanother embodiment, a sealant material may comprise a hardfacingmaterial (e.g., a nickel or cobalt alloy) applied at least within thegaps by thermal spraying. In yet a further embodiment, a sealantmaterial may comprise polyurethane, or another suitable polymeric,metal, alloy, or other material. In another embodiment, a substantiallycontinuous superhard bearing surface 216 may be at least partiallyformed by depositing a layer of diamond onto the surface 216 and intogaps between the segments 226 a-f.

FIGS. 3 and 4 illustrate top plan and isometric views, respectively, ofdifferent embodiments of tilting pads that may be employed in ahydrodynamic tilting pad bearing assembly according to an embodiment. Inparticular, FIG. 3 illustrates a tilting pad 304 that may include aplurality of superhard bearing segments 326 a-d, each of which includesa superhard table 318 with a superhard bearing surface 316 bonded to asubstrate (not shown). The superhard table 318 and substrate (not shown)is optionally bonded or otherwise connected to a support plate 322.

The superhard bearing segments 326 a-d each may include an outer edgeregion 332 and an interior edge region 334. The superhard bearingsegments 326 a-d may be configured with a serrated geometry at theinterior edge regions 334. Such a configuration may allow adjacentsuperhard bearing segments 326 a-d to mate and at least partiallyinterlock, while also defining seams 336 of a geometry that limits fluidleakage radially through the gaps between adjoining superhard bearingsegments 326 a-d.

The illustrated and described seams between adjacent superhard bearingsegments are merely illustrative, and seams between superhard bearingsegments and/or configurations of interior edge regions of superhardbearing segments may have any number of configurations. For, instance, aset of interconnecting superhard bearing segments may have substantiallystraight, serrated, saw-toothed, sinusoidal-like, curved, or otherwiseshaped interior edge regions, or any combination of the foregoing.Moreover, some portions of an interior edge region may have oneconfiguration of shape while another portion of an interior edge regionon the same superhard bearing segment may have a different configurationor shape. Accordingly, different superhard bearing segments may alsoinclude different mating geometry or other configurations.

As discussed herein, a tilting pad bearing assembly may be utilizedwhere certain conditions are met, or in any number of othercircumstances or industries. For instance, an application may beidentified where it would benefit to use a superhard bearing elementincluding a superhard material; however, the superhard material may haveassociated production limits (e.g., size, availability, etc.). Where thesuperhard bearing element has a size, shape, or other feature(s)exceeding such production limits, the superhard bearing element may befashioned out of multiple individual segments that collectively define asuperhard bearing surface of the superhard bearing element. In othercases, however, the type of material used in the superhard bearingelement may not have the same production limits as PDCs or othersuperhard materials, or the superhard bearing element may be sized smallenough to allow a single superhard or other material to be used to formthe superhard bearing surface. FIG. 4 illustrates an embodiment in whicha tilting pad 404 may have a size and/or comprise a material configuredsuch that a single segment may form a substantially continuous superhardbearing surface 416. In particular, the tilting pad 404 may include asuperhard table 418 bonded to a substrate 420. The substrate may in turnbe bonded to a support plate 422. Optionally, the support plate 422 isoversized relative to the substrate 420; however, the support plate 422may also be about the same size or smaller than the substrate 420. Inthis embodiment, a single segment 426 may define substantially theentire superhard bearing surface 416. For instance, the segment 426 mayexhibit a length and/or width that may measure approximately 15 mm by 10mm, such that a single superhard table 418 made from polycrystallinediamond or other materials may be fashioned into the desired shape, evenin the absence of providing multiple interlocking, adjoining, oradjacent segments. In other embodiments, the segment 426 may have othersizes and may even exceed a maximum size available for PCDs. Forinstance, other superhard materials (e.g., tungsten carbide) may be usedto form the superhard bearing surface 116 using a single, integralsegment.

Any of the above-described hydrodynamic tilting pad bearing assemblyembodiments may be employed in a hydrodynamic tilting pad bearingapparatus. FIGS. 5A and 5B are isometric cutaway and isometric partialcross-sectional views, respectively, of a hydrodynamic tilting padthrust-bearing apparatus 500 according to an embodiment. Thehydrodynamic tilting pad thrust-bearing apparatus 500 may include arotor 554 and a stator 556. The stator 556 may be configured as any ofthe described embodiments of hydrodynamic tilting pad bearingassemblies, or may include any of the described embodiments of superhardbearing elements or tilting pads. The stator 556 may include a supportring 502 and a plurality of tilting pads 504 mounted or otherwiseattached to the support ring 502, with each of the tilting pads 504having a superhard bearing surface 516. The tilting pads 504 may betilted and/or tilt relative to a rotational axis 505 of the hydrodynamictilting pad apparatus 500 and/or one or more surfaces of the supportring 502. The tilting pads 504 may be fixed at a particular tilt, may bemanually adjusted to exhibit a particular tilt, may self-establish at aparticular tilt, or may be otherwise configured. The terms “rotor” and“stator” refer to rotating and stationary components of the tilting padbearing apparatus 500, respectively, although the rotating andstationary status of the illustrated embodiments may also be reversed.For instance, the support ring 502 and tilting pads 504 may remainstationary while a support ring 558 rotates.

The rotor 554 may be configured in any suitable manner, including inaccordance with embodiments described herein. The rotor 554 may includea support ring 558 connected to one or more superhard bearing segments562. The rotor 554 may include a substantially continuous superhardbearing surface which is generally adjacent the superhard bearingsurfaces 516 of the stator 556. A fluid film may be formed between thesubstantially continuous superhard bearing surface of the rotor 554 andthe superhard bearing surfaces 516 of the stator 556. In someembodiments, the superhard bearing surface of the rotor 554 may beformed of a single material and may be formed of a same or differentmaterial relative to materials used to form the tilting pad superhardbearing elements 504. In other embodiments, such as shown in FIGS. 6Aand 6B, the superhard bearing surface of the rotor 554 may be defined atleast partially by a plurality of circumferentially-adjacent superhardbearing segments 562 (e.g., a plurality of superhard compacts), each ofwhich includes an outer superhard bearing surface 560 defining at leasta portion of the substantially continuous superhard bearing surface ofthe rotor 554. The superhard bearing segments 562 may be mounted orotherwise attached to a support ring 558 by brazing, a press-fit,mechanical fasteners, or in another manner.

As shown in FIG. 5A, a shaft 564 may be coupled to the support ring 558and operably coupled to an apparatus capable of rotating the shaftsection 564 in a direction R (or in an opposite direction). An apparatuscapable of providing such rotation may include a downhole motor. Forexample, the shaft 564 may extend through and may be secured to thesupport ring 558 of the rotor 554 by press-fitting or a threadedconnection that couples the shaft 564 to the support ring 502, or byusing another suitable technique. A housing 566 may be secured to thesupport ring 502 of the stator 556 by, for example, press-fitting orthreadly coupling the housing 566 to the support ring 502, and mayextend circumferentially about the shaft 564, the stator 556, and therotor 554.

The operation of the hydrodynamic tilting pad bearing apparatus 500 isdiscussed in more detail with reference to FIG. 5B. FIG. 5B is anisometric partial cross-sectional view in which the shaft 510 andhousing 511 are not shown for clarity. In operation, drilling fluid,mud, or some other fluid may be pumped between the shaft 510 and thehousing 511, and between the tilting pads 504 of the stator 556 and thesuperhard bearing segments 562 of the rotor 554. More particularly,rotation of the rotor 554 at a sufficient rotational speed may sweep thefluid onto superhard bearing surfaces 516 of the stator 556 and mayallow a fluid film 568 to develop between the superhard bearing surfaces560 of the rotor 554 and the superhard bearing surfaces 516 of thestator 556. The fluid film 568 may develop under certain operationalconditions in which the rotational speed of the rotor 556 issufficiently great and the thrust load is sufficiently low.

The stator 556 may include tilting pads 504 that are optionally made ofmultiple segments 526. Moreover, in at least some embodiments, thetilting pads 504 may be configured to tilt as described herein. In suchan embodiment, the tilting pads 504 may be positioned at a fixed tiltangle or at a configurable or self-establishing tilt angle. The tiltingpads 504 of the stator 556 may have a leading edge 570 at a differentposition than a trailing edge 572 relative to the rotor 554. Forinstance, in FIG. 5B, the tilting pads 504 may be tilted such that agreater separation exists between the tilting pads 504 and the superhardbearing segments 562 at the leading edge 570 than at the trailing edge572. Under such circumstances, the lubricant film 568 may have avariable thickness across the tilting pad 504. In this particularembodiment, a higher lubricant film thickness may exist at the leadingedge 570 than at the trailing edge 572.

Under certain operational conditions, the pressure of the fluid film 568may be sufficient to substantially prevent contact between the superhardbearing surfaces 560 of the rotor 554 and the superhard bearing surfaces516 of the stator 556 and may thus substantially reduce wear of thesuperhard bearing segments 562 and the tilting pads 504. When the thrustloads exceed a certain value and/or the rotational speed of the rotor554 is reduced, the pressure of the fluid film 568 may not be sufficientto substantially prevent the superhard bearing surfaces 560 of the rotor554 and the superhard bearing surfaces 516 of the stator 556 fromcontacting each other. Under such operational conditions, thehydrodynamic tilting pad bearing apparatus 500 is not operated as ahydrodynamic bearing. Thus, under certain operational conditions, thehydrodynamic tilting pad bearing apparatus 500 may be operated as ahydrodynamic bearing apparatus and under other conditions thehydrodynamic tilting pad bear apparatus 500 may be operated so that thesuperhard bearing surfaces 516, 560 contact each other during use or apartially developed fluid film is present between the superhard bearingsurfaces 516, 560. However, the tilting pads 504 and superhard bearingsegments 562 may comprise superhard materials that are sufficientlywear-resistant to accommodate repetitive contact with each other, suchas during start-up and shut-down of a subterranean drilling or othersystem employing the hydrodynamic tilting pad bearing apparatus 500 orother operational conditions not favorable for forming the fluid film568. In still other embodiments, a backup roller or other bearing (notshown) may also be included for use during certain operationalconditions, such as during start-up, or as the fluid film 558 develops.

FIGS. 6A and 6B illustrate top isometric views and isometric partialcross-sectional views, respectively, of the rotor 554 and illustrate anembodiment of a configuration of multiple superhard bearing segments 562a, 562 b in more detail. In particular, in the illustrated embodiment,the superhard bearing segments 562 a, 562 b may be a superhard compact(e.g., a PDC) that includes a superhard table 574 bonded to a substrate576. Each superhard table 574 may include a superhard bearing surface560. The superhard bearing surfaces 560 of the superhard tables 574 maycollectively form a substantially continuous superhard bearing surfaceof the stator 556.

An example manner in which the superhard bearing segments 562 a, 562 bmay be assembled together is illustrated in FIGS. 6A and 6B; however, inother embodiments, multiple segments may be assembled together in othermanners, using differing geometries, or using a single material ratherthan a set of multiple segments. In the illustrated embodiment, thesuperhard bearing segments 562 a, 562 b may extend circumferentially ina generally circular manner, and may be secured to the support ring 558using a brazing, press-fit, fastener, or other attachment mechanism.There may be a plurality of outer segments 562 a and a plurality ofinner segments 562 b. The outer segments 562 a may include, in someembodiments, an outer edge section 586 and at least one interior edgesection 588. The outer edge sections 586 of the collective set of outersegments 562 may define all or a portion of the outermost edge of thesuperhard bearing surface 560. Similarly, the inner segments 562 b mayinclude, in some embodiments, an inner edge section 588 and at least oneouter edge section 586. The outer edge sections 588 of the collectiveset of inner segments 562 b may define all or a portion of the innermostedge of the superhard bearing surface 560. For instance, the innermostedge of the superhard bearing surface 560 may bear against a shaft (seeFIG. 5A).

The interior edge sections 584 of the superhard bearing segments 562 a,562 b may interconnect with, or otherwise correspond to, other of themultiple superhard bearing segments 562 a, 562 b. For instance, in theillustrated embodiment, each outer superhard bearing segment 562 a mayconnect at opposing ends to other outer superhard bearing segments 562 athat extend circumferentially relative thereto. Each outer superhardbearing segment 562 a may also interface or mesh with one or more innersuperhard bearing segment 562 b which extend radially inward relative tothe outer superhard bearing segment 562 a. Such an arrangement is,however, merely exemplary. In other embodiments, there may be more thantwo superhard bearing segments extending radially to form thesubstantially continuous superhard bearing surface, any number ofdifferent segments extending circumferentially to form the substantiallycontinuous superhard bearing surface, or a superhard bearing segment mayinterface with a segment extending at least partially in bothcircumferential and radial directions with respect thereto. Accordingly,a substantially continuous superhard bearing surface may be formed by acollective set of superhard bearing segments 562 a, 562 b each having arespective superhard bearing surfaces 560, and such superhard bearingsegments 562 a, 562 b may be arranged, connected, or shaped in anysuitable manner.

In FIGS. 6A and 6B, each of the interior edge sections 584 may have analternating slot-and-ridge pattern, although such a configuration ismerely illustrative. In other embodiments, the interior edge sections584 may exhibit any of the previously described geometries, such as aserrated, straight, curved, or other geometry. Such geometries mayenable mating adjacent superhard bearing segments together and/orlimiting of fluid leakage through seams between adjacent superhardbearing segments.

Accordingly regardless of the particular arrangement, multiple segmentsform the substantially continuous superhard bearing surface of thestator 556, a set of seams 582 may form between adjoining segments 562a, 562 b. The seams 582 may provide a tortuous or winding path thatlimits fluid leakage radially through the seams 582. The seams 582 maycorrespond to a relatively small gap 580 existing between the segments562 a, 562 b. Although not necessary, the size of the gaps 580 may bethe same or similar to those described previously with respect toexemplary tilting pad superhard bearing elements. For instance, the gaps580 may have a width of about 0.001 mm to about 3.5 mm, moreparticularly a width of about 0.0025 mm to about 2.5 mm, and moreparticularly a width of about 0.125 mm to about 1.25 mm. Moreparticularly still, the gaps 580 may have a width from about 0.005 mm upto about 1.0 mm. The gaps 580 are optionally filled with a sealantmaterial as described herein.

The concepts used in the hydrodynamic tilting pad bearing assemblies andapparatuses described herein may also be employed in tilting pad radialbearing assemblies and apparatuses. FIGS. 7A to 7C are isometric,exploded, and isometric partial cross-sectional views, respectively, ofa hydrodynamic tilting pad radial bearing apparatus 600 according to yetanother embodiment. The hydrodynamic tilting pad radial bearingapparatus 600 may include an inner race 654 (e.g., a runner or rotor)that may have an interior surface 667 defining an opening 655 forreceiving a shaft or other component. The inner race 654 may alsoinclude a plurality of circumferentially and/or longitudinally adjacentsuperhard bearing segments 662 (e.g., a plurality of superhard compacts)at or near an exterior surface 669 of the inner race 654, each of whichmay include a convexly-curved superhard bearing surface 660.

The hydrodynamic tilting pad radial bearing apparatus 600 may furtherinclude an outer race 656 (e.g., a stator) configured to extend aboutand/or receive the inner race 654. The outer race 656 may include aplurality of circumferentially-spaced tilting pads 604, each of whichmay include a superhard bearing surface 616. The superhard bearingsurface 616 may be substantially planar, although in other embodimentsthe superhard bearing surface 616 may be a concavely-curved superhardbearing surface to generally correspond to shapes of convexly-curvedsuperhard bearing surfaces of the inner race 654. The terms “rotor” and“stator” refer to rotating and stationary components of the radialbearing system 600, respectively. Thus, if the inner race 654 isconfigured to remain stationary, the inner race 654 may be referred toas the stator and the outer race 656 may be referred to as the rotor.

The hydrodynamic tilting pad radial bearing apparatus 600 may beemployed in a variety of mechanical applications. For example, rotarydrill bits may benefit from a radial bearing apparatus disclosed herein.More specifically, the inner race 654 may be mounted or affixed to aspindle of a rotary drill bit and the outer race 656 may be affixed toan inner bore such that an outer race 656 and inner race 654 may beassembled to form the radial bearing system 600.

With continued reference to FIG. 7A, rotation of a shaft (not shown)secured to the inner race 654 may effect rotation of the inner race 654relative to the outer race 656. Drilling fluid or other fluid orlubricant may be pumped between the superhard bearing surfaces 616 ofthe inner race 654 and the superhard bearing surfaces 660 of the outerrace 656. When the inner race 654 rotates, the leading edge sections 670of the tilting pads 604 may sweep lubricant (e.g., drilling fluid orother lubricant) onto the superhard bearing surfaces 660 of the outerrace 656. As previously described with respect to the hydrodynamictilting pad bearing apparatus 500, at sufficient rotational speeds forthe inner race 654, a fluid film may develop between the superhardbearing surfaces 616, 660 of the tilting pads 604 and the superhardbearing segments 662, and may develop sufficient pressure to maintainthe superhard bearing surfaces 616 and the superhard bearing surfaces660 apart from each other. Accordingly, wear on the tilting pads 604 andsuperhard bearing segments 662 may be reduced compared to when directcontact between the tilting pads 604 and superhard bearing segments 662occurs.

As further illustrated in FIGS. 7A and 7B, the outer race 656 includes asupport ring 602 extending about an axis 606. The support ring 602 mayinclude an interior channel 603 configured to receive a set of tiltingpad superhard bearing elements 604 distributed circumferentially aboutthe axis 606. Each tilting pad 604 may comprise a superhard table 618including a superhard bearing surface 616. The superhard bearing surface616 may be curved (e.g., concavely-curved) or substantially planar and,in some embodiments, may include a peripheral chamfer. In otherembodiments, the superhard bearing surface 616 may be otherwise curved,lack a chamfered edge, may have another contour or configuration, or anycombination of the foregoing. Each superhard table 618 may be bonded toa corresponding substrate 620. Further, each superhard bearing surface616 may be tilted circumferentially relative to an imaginary cylindricalsurface. The superhard tables 618 and substrates 620 may be fabricatedfrom the same materials described above for the tilting pads 104 shownin FIGS. 1A and 1B.

Each superhard bearing surface 616 of a corresponding tilting pad 604may be tilted in a manner that facilities sweeping in of a lubricant orother fluid to form a fluid film between the inner race 654 and theouter race 656. Each tilting pad 604 may be tilted and/or tilt about anaxis that is generally parallel to the central axis 606. As a result,each tilting pad 604 may be tilted at an angle relative to the inner andouter surfaces of the ring 602 and in a circumferential fashion suchthat the leading edges 670 of the tilting pads 604 are about parallel tothe central axis 606. The leading edge 670 may help to sweep lubricantor another fluid onto the superhard bearing surfaces 616 of the stator656 to form a fluid film in a manner similar to the tilting pads 504shown in FIGS. 5A and 5B. More particularly, when the inner race 654 isconcentrically positioned relative to the outer race 656, the leadingedges 670 may be offset relative to the outer edge 669 of the outer race656, and by a distance that is larger than a distance between the outerrace 656 and a trailing edge of the superhard bearing elements 604. Itshould be noted that in other embodiments, the radial bearing apparatus600 may be configured as a journal bearing. In such an embodiment, theinner race 654 may be positioned eccentrically relative to the outerrace 656.

In some embodiments, the tilting pad 604 may be formed from a pluralityof superhard bearing segments 626 that collectively define a respectivetilting pad 604 and/or superhard bearing surface 616. Each superhardbearing segment 626 may be substantially identical, or the superhardbearing segments 626 may be different relative to other of the superhardbearing segments 626. In some embodiments, the superhard bearingsegments 626 each include a superhard table 618 bonded to a substrate620 as described herein. Optionally, the substrate 620 may be connectedor supported relative to a support plate 622, the support ring 602, orother material or component. The support plate 622 may be a singlecomponent or segment and used to facilitate assembly of the multiplesegments 626 into the superhard bearing element 604, although in otherembodiments the support plate 622 may also include multiple assembledsegments.

With continued reference to FIGS. 7A and 7B, the seams 636 may be formedbetween circumferentially and/or longitudinally adjacent to thesuperhard bearing elements 604. As with the hydrodynamic tilting padbearing assembly 100 described above, the edges of the superhard bearingsegments 626 may have any number of configurations or shapes, and maycorrespond to or interlock with adjoining edges in any number ofdifferent manners. Further, sealant materials may be disposed within agap (not shown) that may be formed between adjacent superhard bearingsegments 662 to help further prevent fluid leakage through the seams636.

As further illustrated in FIGS. 7A and 7C, the inner race 654 of theradial bearing apparatus 600 is shown with a support ring 658 connectedto a plurality of circumferentially and longitudinally-adjacentsuperhard bearing segments 662 assembled together to form asubstantially continuous superhard bearing element 626 and substantiallycontinuous superhard bearing surface. In other embodiments, an outerrace of a radial bearing system may include a plurality superhardbearing segments that are only circumferentially-spaced around the innerrace 654, or a plurality of superhard bearing segments that are onlylongitudinally spaced with respect to the inner race 654. In still otherembodiments, the inner race 654 may define a superhard bearing surfacethat is formed from only a single segment, such that there are notmultiple segments assembled together. For instance, a single segment maybe used where the size of the inner race 654 is sufficiently small thatthe material forming the superhard bearing surface 660 may be formed asa single material. Under some conditions, such as where a materialforming the superhard bearing surface has limited productionconstraints, the superhard bearing surface 660 may be formed frommultiple segments.

As noted previously, the plurality of superhard bearing segments 662 maybe distributed circumferentially and/or longitudinally relative to theaxis 606. Where the superhard bearing segments 662 include a superhardtable 674 and/or a substrate 676, the superhard tables 674 andsubstrates 676 may be fabricated from the same materials described abovefor the superhard bearing segments 104 shown in FIGS. 1A to 1D. One ormore seams 682 may be formed between adjacent superhard bearing segments662. As with the tilting pad bearing assembly 100 described above, theseams may follow slot-and-ridge, serrated, straight, curved or otheredge geometries. Further, if desired, any of the previously describedsealant materials may be disposed within a gap (not shown) that may beformed between adjacent superhard bearing segments 662 to help furtherprevent fluid leakage through the seams 682.

The support ring 658 of the inner race 654 may include acircumferentially extending recess configured to receive the pluralityof superhard bearing segments 662. The superhard bearing segments 662may be secured within the recess or otherwise secured to the supportring 658 by brazing, press-fitting, using fasteners, or another suitabletechnique. The support ring 658 may also define an interior surface 667defining an opening 655 that is capable of receiving, for example, ashaft of a motor from a downhole motor assembly or other apparatus.

FIGS. 8A through 8C are isometric, top plan, and isometriccross-sectional views, respectively, of a thrust-bearing assembly 900according to another embodiment. The bearing assembly 900 includes asupport ring 902 that carries a plurality of circumferentially-spacedtilting bearing elements 904. Like the tilting pads 104, the tiltingbearing elements 904 may include, for instance, fixed tilting bearingelements, adjustable titling bearing elements, self-establishing tiltingbearing elements, other bearing elements, or combinations of theforegoing.

The tilting bearing elements 904 of the illustrated embodiment generallyhave a cylindrical geometry, and may be distributed circumferentiallyabout a thrust axis 906, along which a thrust force may be generallydirected during use. In other embodiments, the bearing surface 916 ofeach of the tilting bearing elements 904 may have a generallyelliptically shaped geometry, a generally pie-shaped geometry, agenerally rectangular geometry, combinations thereof, or any othersuitable individual geometry. Each tilting bearing element 904 may belocated circumferentially adjacent to another tilting bearing element904, with a gap 908 or other offset therebetween. Each tilting bearingelement 904 may include a discrete, unitary, superhard bearing surface916, such that the tilting bearing elements 904 collectively provide anon-continuous superhard bearing surface.

To support the tilting bearing elements 904 of the bearing assembly 900,the support ring 902 may define multiple recesses 910 for receiving thetilting bearing elements 904. In other embodiments, the support ring 902may define a channel and the tilting bearing elements 904 may be placedwithin the channel. The tilting bearing elements 904 may be supported orat least partially secured within the support ring 902 in any suitablemanner. For instance, a pivotal connection may be used to secure thetilting bearing elements 904 within the support ring 902, although anyother suitable securement or attachment mechanism may also be utilized.Similar to the support ring 102, the support ring 902 may also includean inner peripheral surface defining an aperture 914. The aperture 914may be generally centered about the thrust axis 906, and may be adaptedto receive a shaft (e.g., a downhole drilling motor shaft).

Each tilting bearing element 904 optionally includes multiple layers orother components. For instance, each tilting bearing element 904 may bea superhard bearing element or superhard compact that includes asuperhard table 918 bonded to a substrate 920. The superhard table 918and the substrate 920 may be fabricated from the same materialsdescribed above for the tilting bearing elements 104 shown in FIGS. 1Aand 1B.

Similar to the tilting pads 104, the tilting bearing elements 904 may beused in connection with a runner or other bearing assembly. Like thebearing assembly 100, the thrust-bearing bearing assembly 900 may rotaterelative to a runner or other bearing assembly while a lubricant orother fluid floods the thrust-bearing bearing assembly 900. As thethrust-bearing bearing assembly 900 is rotated, a fluid film separatingthe runner from the superhard bearing surfaces 916 may develop. Forfavorable use of the hydrodynamic forces within the lubricant, thetilting bearing elements 904 may tilt which may result in a higherlubricant film thickness existing at a leading edge (i.e., an edge of atilting bearing element 904 that would be traversed first by a line on arunner/stator while the thrust-bearing assembly 900 moves in thedirection of rotation), than at a trailing edge (i.e., an edge of atilting bearing element 904 that would be traversed last by a line on arunner/stator, while the thrust-bearing assembly 900 moves in thedirection of rotation).

The degree to which the tilting bearing elements 904 rotate or tilt maybe varied in any suitable manner. For example, in an embodiment, thetilting bearing elements 904 may be tilted about respective axes thatextend generally radially from the thrust axis 906 and through eachrespective tilting bearing element 904. The tilting bearing element 904may be connected to the support ring 902 by way of a rotatableconnection. For instance, in FIGS. 8A-8C, the tilting bearing element904 may be rotatably connected to a retaining feature, such as a pin924. The pin 924 may define or correspond to a tilt axis 925 (shown inFIG. 8B). The pin 924 may be secured within the support ring 902 in amanner that allows the tilting bearing element 904 to rotate relative tothe axis 925 and the pin 924. In other embodiments, the tilting bearingelement 904 may be fixedly attached to the pin 924 and the pin 924 maybe rotatably secured within the support ring 902 in a manner that allowsthe tilting bearing element 904 and the pin 924 to rotate relative tothe support ring 902. Moreover, in other embodiments, where the tiltingbearing element 904 is fixedly attached to the pin 924, the pin 924 maybe moveable or adjustable between various fixed positions such that thetilting bearing element 904 may be manually adjusted to exhibit aselected tilt. In other embodiments, each recess 910 may include a pairof protrusions extending radially from a lateral surface of the recess910 and the tilting bearing element 904 may include apertures or groovesconfigured that receive the protrusions of the recesses 910 to form arotatable connection between the support ring 902 and the tiltingbearing element 904.

In an embodiment, the tilting bearing element 904 and/or the pin 924 mayrotate or tilt by about zero to about positive or negative twentydegrees relative to the tilt axis 925 or other horizontal axis. In someembodiments, the superhard bearing surfaces 916 of the respectivetilting bearing elements 904 may also tilt from about zero to aboutpositive or negative twenty degrees. In other embodiments, the tiltingbearing elements 904 and/or the superhard bearing surface 916 may rotatefrom about zero to about fifteen degrees, such as a positive or negativeangle (A) of about 0.5 to about 3 degrees (e.g., about 0.5 to about 1degree or less than 1 degree) relative to the axis 925 of the pin 924(as shown in FIG. 8E). Like the support ring 102, the support ring 902may be configured for bidirectional rotation. In such a case, thetilting bearing element 904 and/or the pin 924 may be allowed to rotatein clockwise and counterclockwise directions. For instance, thesuperhard bearing surface 916 may be rotated to a position anywherebetween a positive or negative angle of about twenty degrees relative tothe axis 925, such as a positive or negative angle (A) of about 0.5 toabout 3 degrees (e.g., about 0.5 to about 1 degree or less than 1degree) relative to the axis 925 of the pin 924. Like the pin 124, thepin 924 may be used to allow the tilting bearing elements 904 toselectively rotate. In still other embodiments, the tilting bearingelements 904 may be fixed at a selected magnitude of tilt, or may bemanually set to a selected magnitude of tilt with or without beingself-establishing.

As described above, according to some embodiments, an individualsuperhard bearing element or compact forms each tilting bearing element904. The tilting bearing elements 904 may include various mechanisms forfacilitating rotation, translation, or other positioning of the tiltingbearing element 904. FIGS. 8D through 8F are isometric, cross-sectional,and bottom views, respectively, of the tilting bearing element 904. Inan embodiment, the tilting bearing element 904 may, for instance, bemachined or otherwise formed to include a recess 927 (e.g., a blind orthrough hole), an opening, or other structure into which the pin 924 (orother structural member) may be at least partially received or secured.The recess 927 may be machined or otherwise formed in a base portion ofthe tilting bearing element 904 comprising the substrate 920. In otherembodiments, the recess 927 may be machined or otherwise formed in abase portion of the tilting bearing element 904 comprising anothermaterial layer 922, such as steel or another alloy or other metallicmaterial, attached to the substrate 920 (e.g., a base surface). In otherembodiments, the tilting bearing element 904 may include a plurality ofrecesses. For instance, the tilting bearing element 904 may include asecond recess (not shown) generally perpendicular to the recess 927.Such a configuration may allow a user to alternate insertion of the pin924 between the recess 927 and the second recess such that a user mayrotate the orientation of the tilting bearing element 904 as needed toincrease the useful life of the tilting bearing element 904.

In addition, the tilting bearing element 904 may be machined orotherwise formed to include a pivot 928 for facilitating rotation of thetilting bearing elements 904. For example, the pivot 928 may begenerally hemispherical, rounded, generally cylindrical, or otherwiseconfigured to allow or facilitate tilting of the tilting bearingelements 904. In an embodiment, the pivot 928 may be formed in theadditional material layer 922 attached to a base surface of thesubstrate 920. The additional material layer 922 may be any suitablematerial such as steel or other alloy or another material that isrelatively softer than the substrate 920. In other embodiments, theadditional material layer 922 may be omitted and the substrate 920 maybe directly machined or formed to include the pivot 928. The pivot 928may be formed by computer numerical control (“CNC”) milling,electro-discharge machining, laser-cutting, grinding, combinationsthereof, or other suitable techniques. For example, suitablelaser-cutting techniques are disclosed in U.S. patent application Ser.No. 13/166,007 filed on Jun. 22, 2011, the disclosure of which isincorporated herein, in its entirety by this reference.

In some embodiments, similar to the tilt axis 125, the tilt axis 925 ofthe tilting bearing elements 904 may be substantially centered betweenthe leading and trailing edges of the tilting bearing elements 904. Forinstance, where the support ring 902 may be configured forbi-directional rotation, the tilt axis 925 of the tilting bearingelements 904 may be substantially centered relative to either ofopposing edges of the tilting elements 904 being the leading or trailingedge, based on a selected direction of rotation. In other embodiments,the tilt axis 925 of a tilting bearing element 904 may be offsetrelative to an axis of symmetry on the bearing surface 916. An axis ofsymmetry is a line that divides the bearing surface into twosubstantially symmetrical parts in such a way that the bearing surfaceon one side is substantially the mirror image of the bearing surface onthe other side. For instance, where the support ring 902 is part of arotor configured for only unidirectional rotation, the tilt axis 925 ofthe tilting bearing element 904 may be offset such that the tilt axis925 is closer to one of the leading edge or the trailing edge of thetilting bearing element 904. In other embodiments, a tilt axis may beoffset from axes of symmetry on the bearing surface 916 on the tiltingbearing element 904 despite a rotor being configured for bidirectionalrotation, or a tilt axis may be substantially centered relative to anaxis of symmetry on the bearing surface 916 of the tilting bearingelement 904 despite a rotor being configured for unidirectionalrotation.

In other embodiments, one or more tilting bearing elements may exhibitother features to facilitate tilting of the tilting bearing elements.For example, FIGS. 9A-9C illustrate isometric, top partial plan, andpartial cross-sectional views, respectively, of a thrust-bearingassembly 1000 including tilting bearing elements exhibiting otherconfigurations or geometries according to an embodiment. Thethrust-bearing bearing assembly 1000 may include a support ring 1002that carries a plurality of circumferentially-spaced tilting bearingelements 1004. In the illustrated embodiment, the tilting bearingelements 1004 generally have a generally cylindrical geometry, and maybe distributed about a thrust axis 1006, along which a thrust force maybe generally directed during use. In other embodiments, the tiltingbearing elements 1004 may have a generally elliptical shaped geometry, agenerally pie-shaped geometry, a generally rectangular shaped geometry,combinations thereof, or any other suitable individual geometry. Eachtilting bearing element 1004 may be located circumferentially adjacentto another tilting bearing element 1004, with a gap 1008 or other offsettherebetween. Each tilting bearing element 1004 includes a discrete,unitary superhard bearing surface 1016, such that the tilting bearingelements 1004 collectively provide a non-continuous superhard bearingsurface.

To support the tilting bearing elements 1004 of the bearing assembly1000, the support ring 1002 may define a plurality of recesses 1010 forreceiving the tilting bearing elements 1004. The tilting bearingelements 1004 may be supported or at least partially secured within thesupport ring 1002 via one or more retaining features. In the illustratedembodiment, threaded retaining elements 1030 including head portions1032 may be used to secure the tilting bearing elements 1004 within thesupport ring 1002, although other suitable securement or attachmentmechanism may also be utilized. For example, press-fit, welded, locked,or brazed in-place pins may be used instead of the threaded retainingelements 1030. Similar to the support rings 102 and 902, the supportring 1002 may also include an inner peripheral surface defining anaperture 1014. The aperture 1014 may be generally centered about thethrust axis 1006 and may be adapted to receive a shaft.

Each tilting bearing element 1004 optionally includes multiple layers orother components. For example, each tilting bearing element 1004 may bea superhard bearing element or compact that includes a superhard table1018 bonded to a substrate 1020. The superhard table 1018 and thesubstrate 1020 may be configured similar to the superhard table 118 andthe substrate 120 described in relation to FIG. 1B. Moreover, similar tothe tilting pads 104, the tilting bearing elements 1004 may be used inconnection with a runner or other bearing assembly.

Thrust-bearing assembly 1000 may include various features forfacilitating rotation, translation, or other positioning of the tiltingbearing elements 1004. FIGS. 9E and 9F are isometric and cross-sectionalviews, respectively, of a single one of the tilting bearing elements1004. As shown, the tilting bearing element 1004 may include a bottomsurface and a pivot 1034 formed on the bottom surface. The pivot 1034may comprise a generally semi-cylindrical convex portion disposedbetween a pair of planar portions. In other embodiments, the convexportion of the pivot 1034 may form substantially the entire portion ofthe bottom surface of the tilting bearing element 1004. The pivot 1034may define or correspond to a tilt axis 1025 such that the tiltingbearing element 1004 may rotate or tilt relative to the tilt axis 1025.In an embodiment, the convex portion of the pivot 1034 may extend acrossthe entire bottom surface of the tilting bearing element 1004. In otherembodiments, the convex portion of the pivot 1034 may extend across onlya portion of the bottom surface of the tilting bearing element 1004. Inyet other embodiments, the pivot 1034 may include a plurality of convexportions. For example, the pivot 1034 may include three convex portionsspaced from one another, with each convex portion being positioned alonga linear path on the bottom surface of the tilting bearing element 1004.

In an embodiment, the pivot 1034 may be formed in the substrate 1020. Inother embodiments, the pivot 1034 may be formed in an additional layerattached to the base surface of the substrate 1020. The additionalmaterial layer may be any suitable material such as steel or other alloyor another metallic material that is relatively softer than thesubstrate 1020. Like the pivot 928, the pivot 1034 may be formed by CNCmilling, electro-discharge machining, laser-cutting, grinding,combinations thereof, or other suitable techniques.

In some embodiments, the tilt axis 1025 or the pivot 1034 may besubstantially centered relative to an axis of symmetry on the bearingsurface 1016 of the corresponding tilting bearing element 1004. In otherembodiments, the tilt axis 1025 may be offset relative to axes ofsymmetry on the bearing surface 1016 of the corresponding tiltingbearing element 1004. For instance, where the support ring 1002 is partof a rotor configured for only unidirectional rotation, the axis ofrotation of the tilting bearing element 1004 may be offset such that thetilt axis 1025 is closer to one edge of the tilting bearing element1004. In other embodiments, a tilt axis may be offset from axes ofsymmetry on the bearing surface 1016 of the tilting bearing element 1004despite a rotor being configured for bidirectional rotation, or a tiltaxis may be substantially centered relative to an axis of symmetry ofthe bearing surface 1016 of the tilting bearing element 1004 despite arotor being configured for unidirectional rotation.

Optionally, the recesses 1010 of the support ring 1002 may be configuredto help facilitate tilting of the tilting bearing elements 1004. Forinstance, the recesses 1010 may include a base surface having a pair ofgenerally planar portions 1036 separated by a concave portion 1038 asshown in FIG. 9D. The concave portion 1038 of the recess 1010 may helpfacilitate tilting or rotation of the tilting bearing element 1004within the recess 1010. The recess 1010 may be rounded, generallysemi-hemispherical, generally semi-cylindrical, etc., and may have adifferent radius than pivot 1034. For example, the pivot 1034 of thetilting bearing element 1004 may be configured to rock or tilt in theconcave portion 1038 of the recess 1010. In other embodiments, therecesses 1010 of the support ring 1002 may include a generally planarbottom portion upon which the pivot 1034 may rock or tilt.

In addition to the pivot 1034, the tilting bearing elements 1004 mayinclude other features for facilitating rotation, translation, or otherpositioning of the tilting bearing elements 1004. For instance, thetilting bearing element 1004 may be machined or otherwise formed toinclude a groove 1040 or other retaining feature into which at least aportion of the head portion 1032 of the threaded retaining element 1030(or other retaining feature or structure) may be at least partiallyreceived or secured (shown best in FIG. 9C). As illustrated, thethreaded retaining elements 1030 may be threadly received in receivingholes 1037 formed in an upper surface of the support ring 1002 betweenadjacent ones of the tilting bearing elements 1004 in the gaps 1008. Atleast a portion of the head portion 1032 of each threaded retainingelement 1030 may be positioned within the groove 1040 of the tiltingbearing element 1004 in such a manner that it secures the tiltingbearing elements 1004 within the recesses 1010, while allowing limitedtilting of the tilt bearing element 1004 relative to the support ring1002. For instance, the groove 1040 and the head portion 1032 of thethreaded retaining elements 1030 may be positioned and configured suchthat the tilting bearing element 1004 may selectively tilt relative tothe support ring 1002 until the head portion 1032 engages one of theside walls of the groove 1040.

In an embodiment, the groove 1040 may have a width W and a depth D(shown in FIG. 9F). The depth D of the groove 1040 may extend between abase of the groove and a lateral surface of the tilting bearing element1004. The depth D may be about 0.1 inches to about 0.4 inches, such asabout 0.15 inches to about 0.25 inches. In other embodiments, the depthD of the groove 1040 may be greater or smaller. The width W of thegroove 1040 may extend between the opposing sidewalls of the groove1040. In an embodiment, the width W of the groove 1040 may be about 0.1inches to about 0.5 inches, such as about 0.2 inches to about 0.3inches. In other embodiments, the width W of the groove 1040 may bewider or narrower.

Referring again to FIG. 9C, the head portion 1032 of the threadedretaining element 1030 may have a thickness T defined between an uppersurface and a lower surface of the head portion 1032. The head portion1032 may also have an effective length L defined between an outersurface of the shaft of the threaded retaining element 1030 and alateral surface of the head portion 1032.

In an embodiment, the relationship between the width W of the groove1040 and the thickness T of the head portion 1032 may be configured toadjust rotation of the tilting bearing element 1004 relative to thesupport ring 1002. For example, the thickness T of the head portion 1032may be about twenty (20) percent to about ninety five (95) percent; orabout forty (40) percent to about eighty (80) percent of the width W ofthe groove 1040. In other embodiments, the thickness T of the headportion 1032 and the width W of the groove 1040 may be larger or smallerrelative to each other.

In an embodiment, the relationship between the effective length L of thehead portion 1032 and the depth D of the groove 1040 may be configuredto influence rotation of the tilting bearing element 1004 relative tothe support ring 1002. For example, the effective length L of the headportion 1032 may be about thirty (30) percent to about one hundred (100)percent; or about sixty (60) percent to about ninety (90) percent of thedepth D of the groove 1040. In other embodiments, the effective length Lof the head portion 1032 and the depth D of the groove 1040 may belarger or smaller relative to each other.

In an embodiment, the relationship between the effective length L of thehead portion 1032 and the width W of the groove 1040 may be configuredto influence rotation of the tilting bearing element 1004 relative tothe support ring 1002. For example, the width W of the groove 1040 maybe about ten (10) percent to about eighty (80) percent; or about twenty(20) percent to about sixty (60) percent of the effective length L ofthe head portion 1032. In other embodiments, the effective length L ofthe head portion 1032 and the width W of the groove 1040 may be largeror smaller relative to each other.

As described above, the tilting bearing element 1004 may be positionedwithin the recess 1010 such that the tilting bearing element 1004rotates relative to the support ring 1002 about the tilt axis 1025(shown in FIG. 9E). For example, in an embodiment, the tilting bearingelements 1004 and the threaded retaining elements 1030 may be looselyorganized or positioned on and/or in the support ring 1002 such that atleast a portion of the head portions 1032 of the threaded retainingelements 1030 are positioned within the grooves 1040. The threadedretaining elements 1030 may then be selectively tightened or threadedinto the receiving holes 1037 to secure the tilting bearing elements1004 in the recesses 1010. In one embodiment, the threaded retainingelements 1030 may be threaded into the receiving holes 1037 in astar-shape pattern until all of the tilting bearing elements 1004 aresecured in the recesses 1010. In another embodiment, a free end portionof the threaded retaining elements 1030 may be threaded into thereceiving holes 1037. The tilting bearing elements 1004 may then be slidbetween the threaded retaining elements 1030 over the recesses 1010 suchthat at least a portion of the head portions 1032 of the threadedretaining elements 1030 are positioned within the grooves 1040. Then,the threaded retaining elements 1030 may be further threaded ortightened into the receiving holes 1037 to pull the tilting bearingelements 1004 into the recesses 1010 until the tilting bearing elements1004 are secured and positioned therein.

In an embodiment, the tilting bearing element 1004 may rotate or tiltfrom about zero to about positive or negative twenty degrees relative tothe support ring 1002. In other embodiments, the tilting bearingelements 1004 and/or the superhard bearing surface 1016 may rotate fromabout zero to about fifteen degrees, such as a positive or negativeangle (θ) of about 0.5 to about 3 degrees (e.g., about 0.5 to about 1degree or less than 1 degree) relative to the pivot 1034. Moreover, likethe support ring 102, the support ring 1002 may be configured forbidirectional rotation. In such a case, the tilting bearing element 1004may be allowed to rotate in clockwise and counterclockwise directions.

The pivot 1034, the groove 1040, the threaded retaining elements 1030,or combinations thereof may be used to allow the tilting bearingelements 1004 to selectively rotate. For instance, the tilting bearingelements 1004 may be self-establishing such that based on the lubricantused, the axial forces applied along the thrust axis, the rotationalspeed of the runner or bearing assembly 1000, other factors, orcombinations of the foregoing, the tilting bearing elements 1004 mayautomatically or otherwise adjust to a desired tilt or otherorientation. In still other embodiments, the tilting bearing elements1004 may be fixed at a particular tilt, or may be manually set to aparticular tilt with or without being self-establishing.

Further, the pivot 1034 represents one embodiment of a mechanism forfacilitating rotation, translation, or other positioning of the tiltingbearing elements 1004 so as to provide tilting bearing element superhardbearing surfaces 1016. In other embodiments, other mechanisms may beused. By way of illustration, leveling links, generally semi-ellipticalpivots, generally hemispherical pivots, pivot pins, other elements, orany combination of the foregoing may also be used to facilitatepositioning of the tilted bearing elements 1004 in a tiltedconfiguration.

Referring again to FIGS. 9E and 9F, the tilting bearing element 1004 maybe machined or otherwise formed to include the groove 1040 in a lateralsurface of the substrate 1020. As illustrated, the groove 1040 may havea generally U-shaped cross-section. In other embodiments, the groove1040 may have a generally rectangular cross-section, a generallyV-shaped cross-section, a generally parabolic shaped cross-section, agenerally trapezoidal shaped cross-section, combinations thereof, orother suitable cross-sectional shapes. In an embodiment, the groove 1040may substantially extend around a circumference of the substrate 1020.In other embodiments, the titling bearing element 1004 may include aplurality of grooves or the groove 1040 may extend around only a portionof the circumference of the substrate 1020. For example, a pair ofgrooves, each on opposite sides of the tilting bearing element 1004, mayextend along the lateral surface of the substrate 1020 substantiallyadjacent to the threaded retaining elements 1030. In an embodiment, thegroove 1040 may be machined or otherwise formed in the substrate 1020.In other embodiments, the groove 1040 may be formed in another materiallayer attached to a base surface of the substrate 1020.

FIGS. 10A and 10B are isometric and cross-sectional views, respectively,of a tilting bearing element 1104 according to another embodiment. Thetilting bearing element 1104 generally has a rounded rectangular shapedgeometry. In the illustrated embodiment the tilting bearing element 1104includes a discrete, unitary superhard bearing surface 1116. The tiltingbearing element 1104 optionally includes multiple layers or othercomponents. For example, the tilting bearing element 1104 may be asuperhard bearing element or compact that includes a superhard table1118 bonded to a substrate 1120. The superhard table 1118 and thesubstrate 1120 may be fabricated from the same materials described abovefor the tilting bearing elements 104 shown in FIGS. 1A and 1B.

In an embodiment, the tilting bearing element 1104 may be secured withina support ring (not shown) in a manner that allows the tilting bearingelement 1104 to rotate relative to the support ring. For instance, thetilting bearing element 1104 may be machined or otherwise formed toinclude a recess 1127 (e.g., a partial hole or through hole), anopening, or other structure into which a pin (not shown) attached to thesupport ring may be at least partially received or secured. The recess1127 may define or correspond to a tilt axis 1125 that allows thetilting bearing element 1104 to rotate about the pin relative to thesupport ring. The recess 1127 may be machined or otherwise formed in thesubstrate 1120 or in another metallic material layer, such as steel oranother alloy, attached to the substrate 1120 (e.g., a base surface). Insome embodiments, the tilt axis 1125 and/or the recess 1127 of thetilting bearing element 1104 is substantially centered relative to anaxis of symmetry on the bearing surface 1016 of the tilting bearingelement 1104. In other embodiments, the tilt axis 1125 and/or recess1127 may be offset relative to axes of symmetry on the bearing surface1016 of the tilting bearing element 1104.

In addition, the tilting bearing element 1104 may be machined orotherwise formed to include a pivot 1128 for facilitating tilting orrotation of the tilting bearing element 1104. In the illustratedembodiment, the pivot 1128 may comprise a convex portion formed on thebase surface of the tilting bearing element 1104 that exhibits agenerally semi-elliptical shape. In other embodiments, the tiltingbearing element 1104 may include leveling links, pivotal rockers, otherelements, or any combination of the foregoing may also be used tofacilitate tilting of the tilting bearing elements 1104. The pivot 1128may comprise substantially the entire base surface of the tiltingbearing element 1104. In some embodiments, the pivot 1128 may be formedon only a portion of the base surface of the tilting bearing element1104. The substrate 1120 may be directly machined or formed to includethe pivot 1128. In other embodiments, the pivot 1128 may be formed in anadditional layer attached to a base surface of the substrate 1120. Thepivot 1128 may be formed by CNC milling, electro-discharge machining,laser-cutting, grinding, combinations thereof, or other suitabletechniques.

FIGS. 11A and 11B are isometric cutaway and isometric cross-sectionalviews, respectively, of a thrust-bearing apparatus 1200 that may employany of the disclosed thrust-bearing assemblies according to anotherembodiment. Similar to the thrust-bearing apparatus 500, thethrust-bearing apparatus 1200 may include a rotor 1254 and a stator1256. Generally, the rotor, the stator, or both may include one or moretilting bearing elements. In the illustrated embodiment, the stator 1256may be configured as any of the described embodiments of tilting bearingassemblies, or may include any of the described embodiments of tiltingbearing elements. The stator 1256 may include a support ring 1202 and aplurality of tilting bearing elements 1204 mounted or otherwise attachedto the support ring 1202 by way of a fastener or pin 1224, with each ofthe tilting bearing elements 1204 having a superhard bearing surface1216. The tilting bearing elements 1204 may be tilted and/or tiltrelative to a tilt axis (not shown) extending generally along alongitudinal axis of the pin 1224 or other horizontal axis. The tiltingbearing elements 1204 may be fixed at a particular tilt, may be manuallyadjusted to exhibit a selected tilt, may self-establish at a particulartilt, or may be otherwise configured. The terms “rotor” and “stator”refer to rotating and stationary components of the tilting bearingapparatus 1200, respectively. For instance, the support ring 1202 andtilting bearing elements 1204 may remain stationary while a support ring1258 of the rotor 1254 rotates. However, the rotating and stationarystatus of the illustrated embodiments may be also be reversed.

The rotor 1254 may be configured in any suitable manner, including inaccordance with embodiments described herein. In the illustratedembodiment, the rotor 1254 may include the support ring 1258 and aplurality of non-tilting superhard bearing elements 1262 mounted orotherwise attached to the support ring 1258, with each of the superhardbearing elements 1262 having a superhard bearing surface 1270. As shown,a shaft 1264 may be coupled to the support ring 1258 and operablycoupled to an apparatus capable of rotating the shaft 1264 in adirection R (or in a generally opposite direction), such as a downholemotor. For example, the shaft 1264 may extend through and may be securedto the support ring 1258 of the rotor 1254 by press-fitting or threadlycoupling the shaft 1264 to the support ring 1258 or another suitabletechnique. A housing 1266 may be secured to the support ring 1202 of thestator 1256 and may extend circumferentially about the shaft 1264 andthe rotor 1254. In other embodiments, both the rotor 1254 and stator1256 may include tilting bearing elements. For example, the rotor 1254may include a plurality of tilting bearing elements connected to thesupport ring 1258.

In operation, lubricating fluid (which may include, for example,lubricating fluid, drilling fluid, or mud) may be pumped between theshaft 1264 and the housing 1266, and between the tilting bearingelements 1204 of the stator 1256 and the superhard bearing elements 1262of the rotor 1254. More particularly, rotation of the rotor 1254 at asufficient rotational speed and at appropriate loading conditions, maycause a fluid film 1268 to develop between the superhard bearingsurfaces 1216 of the stator 1256 and the superhard bearing surface 1270of the rotor 1254. The fluid film 1268 may develop under certainoperational conditions in which the rotational speed of the rotor 1254is sufficiently great and the thrust load is sufficiently low. Thetilting bearing elements 1204 of the stator 1256 may have a leading edgeat a different position than a trailing edge relative to the rotor 1254.For example, the tilting bearing elements 1204 may be tilted such that agreater separation exists between the tilting bearing elements 1204 andthe superhard bearing elements 1262 at the leading edge than at thetrailing edge. Under such circumstances, the fluid film 1268 may have avariable thickness across the tilting bearing element 1204. The fluidfilm 1268 can have sufficient pressure to prevent contact between therespective superhard bearing surfaces and, thus, reduce wear of thetilting bearing elements 1204 and the superhard bearing elements 1262.In such a situation, the thrust-bearing apparatus 1200 may be describedas operating hydrodynamically. When the thrust loads exceed a certainvalue and/or the rotational speed of the rotor 1254 is reduced, thepressure of the fluid film 1268 may not be sufficient to prevent thesuperhard bearing surfaces 1270 of the rotor 1254 and the superhardbearing surfaces 1216 of the stator 1256 from contacting each other.Thus, the thrust-bearing apparatus 1200 may be operated to lubricate thecontact area between the superhard bearing surfaces 1270 of the rotor1254 and the superhard bearing surfaces 1216 of the stator 1256 or as ahydrodynamic bearing. It is noted that in other embodiments, the rotoror stator may be configured as any of the previously describedembodiments of thrust-bearing assemblies.

FIGS. 12A to 12C are isometric, exploded, and isometric partialcross-sectional views, respectively, of a radial bearing apparatus 1300according to yet another embodiment. The radial bearing apparatus 1300may include an inner race 1354 (e.g., a runner or rotor) that may havean interior surface 1367 defining an opening 1355 for receiving a shaftor other component. The inner race 1354 may also include a plurality ofcircumferentially adjacent superhard bearing elements 1362 (e.g., aplurality of superhard compacts) extending radially beyond an exteriorsurface 1369 of the inner race 1354, each of which may include aconvexly-curved superhard bearing surface 1370. In the illustratedembodiment, the superhard bearing surfaces 1370 may have a generallyrounded rectangular geometry. In other embodiments, the bearing surfacesmay have a generally elliptical geometry, a generally cylindricalgeometry, a generally wedge-like geometry, combinations of theforegoing, or any other suitable geometric shape.

The radial bearing apparatus 1300 may further include an outer race 1356(e.g., a stator) configured to extend about and/or receive the innerrace 1354. The outer race 1356 may include a plurality ofcircumferentially adjacent tilting bearing elements 1304, each of whichmay comprise a superhard bearing element or compact including asuperhard bearing surface 1316. The superhard bearing surface 1316 maybe substantially planar. However, in other embodiments the superhardbearing surface 1316 may include a convexly-curved superhard bearingsurface to generally mirror the convexly-curved superhard bearingsurfaces of the inner race 1354. The terms “rotor” and “stator” refer torotating and stationary components of the radial bearing system 1300,respectively. Thus, if the inner race 1354 is configured to remainstationary, the inner race 1354 may be referred to as the stator and theouter race 1356 may be referred to as the rotor.

The radial bearing apparatus 1300 may be employed in a variety ofmechanical applications. For example, so-called “rotary cone” rotarydrill bits, pumps, turbo machinery, transmissions, or turbines maybenefit from a radial bearing apparatus discussed herein. In operation,rotation of a shaft (not shown) secured to the inner race 1354 mayaffect rotation of the inner race 1354 relative to the outer race 1356.Lubricating fluid may be pumped through the radial bearing apparatus1300. When the inner race 1354 rotates, the tilting bearing elements1304 may allow for the lubricating fluid to develop a film between thesuperhard bearing surfaces 1316 of the outer race 1356 and the bearingsurfaces 1370 of the inner race 1354. As previously described withrespect to the thrust-bearing apparatus 1200, at sufficient rotationalspeeds for the inner race 1354, a fluid film may develop between thesuperhard bearing surfaces 1316, 1370, of the tilting bearing elements1304 and the superhard bearing elements 1362.

As further illustrated in FIGS. 12A and 12C, the outer race 1356includes a support ring 1302 extending about a rotation axis 1306. Tosupport the tilting bearing elements 1304, the support ring 1302 maydefine a plurality of recesses 1310 for the tilting bearing elements1304. The tilting bearing elements 1304 may be supported or at leastpartially secured within the support ring 1302 in any suitable manner.For example, retaining features, such as pins or fasteners 1324 may beused to secure the tilting bearing elements 1304 within the support ring1302, although any other suitable securement or attachment mechanism mayalso be utilized.

The tilting bearing elements 1304 of the illustrated embodimentgenerally have a rounded rectangular shaped geometry. In otherembodiments, the tilting bearing elements 1304 may have a generallyelliptical shaped geometry, a generally cylindrical shaped geometry, agenerally non-cylindrical shaped geometry, combinations thereof, or anyother suitable shaped geometry. As noted above, each tilting bearingelement 1304 may comprise a superhard bearing element or compact havinga superhard table 1318 including the superhard bearing surface 1316. Thesuperhard bearing surface 1316 may be curved (e.g., convexly-curved) orsubstantially planar and, in some embodiments, may include a peripheralchamfer. In other embodiments, the superhard bearing surface 1316 may beotherwise curved, lack a chamfered edge, may have another contour orconfiguration, or any combination of the foregoing. Further, eachsuperhard bearing surface 1316 may be tilted. For example, the tiltingbearing elements 1304 may be tilted and/or tilt relative to a tilt axis1325 extending generally along a longitudinal axis of the pin 1324 orother axis. The tilting bearing elements 1304 may be fixed at aparticular tilt, may be manually adjusted to exhibit a selected tilt,may be self-establish at a particular tilt, or may be otherwiseconfigured. Each superhard table 1318 may be bonded to a correspondingsubstrate 1320. The superhard tables 1318 and substrates 1320 may befabricated from the same materials described above for the tilting pads104 shown in FIGS. 1A and 1B. The illustrated tilting bearing element1304 may include one or more recesses (not shown), openings, or otherstructures into which the pin 1324 may be at least partially received orsecured. The one or more recesses may be machined or otherwise formed inthe substrate 1320 or in another material layer attached to a basesurface of the substrate 1320. Like the tilting bearing element 1104,the tilting bearing element 1304 may include generally semi-ellipticalpivot 1328 to facilitate tilting of the titling bearing element 1304 inthe recesses 1310.

Each superhard bearing surface 1316 of a corresponding tilting bearingelement 1304 may be tilted in a manner that facilities formation of afluid film between the inner race 1354 and the outer race 1356. Eachtilting bearing element 1304 may be tilted and/or tilt about the tiltaxis 1325. As a result, the bearing surfaces 1316 of the tilting bearingelements 1304 may be tilted at a positive or negative angle relative tothe inner and outer surfaces of the support ring 1302 and in acircumferential fashion. A leading edge (i.e., an edge of a tiltingbearing element 1304 that would be traversed first by a line on arunner/stator while the rotor moves in the direction of rotation) of thetilting bearing element 1304 may help to sweep lubricant or anotherfluid onto the superhard bearing surfaces 1316 of the stator 1356 toform a fluid film in a manner similar to the tilting bearing elements1204 shown in FIGS. 11A and 11B. In other embodiments, the radialbearing apparatus 1300 may be configured as a journal bearing. In suchan embodiment, the inner race 1354 may be positioned eccentricallyrelative to the outer race 1356.

Also illustrated in FIGS. 12A and 12B, the inner race 1354 of the radialbearing apparatus 1300 is shown with a support ring 1358 that includes aplurality of recesses 1372 configured to receive the plurality ofsuperhard bearing elements 1362. The superhard bearing elements 1362 maybe secured within the recess or otherwise secured to the support ring1358 by brazing, welding, locking, press-fitting, using fasteners, oranother suitable technique. The superhard bearing elements 1362 may bedistributed circumferentially and/or longitudinally relative to the axis1306. Where the superhard bearing elements 1362 include a superhardtable 1374 and/or a substrate 1376, the superhard table 1374 andsubstrate 1376 may be fabricated from the same materials described abovefor the tilting pads 104 shown in FIGS. 1A to 1D. In other embodiments,the inner race 1354 may define a superhard bearing surface that isformed from only a single element, such that there are not multiplesuperhard bearing elements. For instance, a single, unitary superhardbearing element may be used where the size of the inner race 1354 issufficiently small.

FIG. 13 is schematic isometric cutaway view of a subterranean drillingsystem 1400 according to another embodiment. The subterranean drillingsystem 1400 may include a housing 1460 enclosing a downhole drillingmotor 1462 (i.e., a motor, turbine, or any other device capable ofrotating an output shaft) that may be operably connected to an outputshaft 1456. A thrust-bearing apparatus 1464 may be operably coupled tothe downhole drilling motor 1462. The thrust-bearing apparatus 1464 maybe configured as any of the previously described thrust-bearingapparatus embodiments. A rotary drill bit 1468 may be configured toengage a subterranean formation and drill a borehole and may beconnected to the output shaft 1456. The rotary drill bit 1468 is showncomprising a bit body 1490 that includes radially and longitudinallyextending blades 1492 with a plurality of PDCs 1494 secured to theblades 1492. However, other embodiments may utilize different types ofrotary drill bits, such as core bits or roller-cone bits. As theborehole is drilled, pipe sections may be connected to the subterraneandrilling system 1400 to form a drill string capable of progressivelydrilling the borehole to a greater depth within the earth.

The thrust-bearing apparatus 1464 may include a stator 1472 that doesnot rotate and a rotor 1474 that may be attached to the output shaft1456 and rotates with the output shaft 1456. As discussed above, thethrust-bearing apparatus 1464 may be configured as any of theembodiments disclosed herein. For example, the stator 1472 may includeat least one tilting bearing element (not shown) similar to or identicalto those shown and described herein. The rotor 1474 may include aplurality of circumferentially-distributed superhard bearing elements(not shown).

In operation, lubricating fluid may be circulated through the downholedrilling motor 1462 to generate torque and rotate the output shaft 1456and the rotary drill bit 1468 attached thereto so that a borehole may bedrilled. A portion of the lubricating fluid may also be used tolubricate opposing bearing surfaces of the stator 1472 and the rotor1474. Optionally, when the rotor 1474 is rotated, the tilting bearingelements of the stator 1472 and/or the rotor 1474 may be configured toassist with formation of a hydrodynamic film between the opposingbearing surfaces by sweeping lubricating fluid between the opposingbearing surfaces.

Although the bearing assemblies and apparatuses described above havebeen discussed in the context of subterranean drilling systems andapplications, in other embodiments, the bearing assemblies andapparatuses disclosed herein are not limited to such use and may be usedfor many different applications, if desired, without limitation. Thus,such bearing assemblies and apparatuses are not limited for use withsubterranean drilling systems and may be used with various othermechanical systems, without limitation.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments are contemplated. The various aspects andembodiments disclosed herein are for purposes of illustration and arenot intended to be limiting. Additionally, the words “including,”“having,” and variants thereof (e.g., “includes” and “has”) as usedherein, including the claims, shall be open ended and have the samemeaning as the word “comprising” and variants thereof (e.g., “comprise”and “comprises”).

The invention claimed is:
 1. A bearing assembly, comprising: a supportring; a plurality of superhard bearing elements positioned on thesupport ring, each of the plurality of superhard bearing elementsincluding a superhard element having a bearing surface and a baseportion bonded to the superhard element; and a plurality of tiltingmembers, each of the plurality of tilting members: attached to orintegrated with a corresponding one of the plurality of base portions;and including an elongated portion defining a longitudinal axis thatdoes not intersect the bearing surface of a corresponding one of theplurality of superhard bearing elements, the elongated portionconfigured to allow a corresponding one of the plurality of superhardbearing elements to tilt about a corresponding tilt axis.
 2. The bearingassembly of claim 1 wherein each of the corresponding tilt axes isoriented radially or axially relative to an axis of rotation of thesupport ring.
 3. The bearing assembly of claim 2 wherein each of theradially-oriented tilt axes extends from the axis of rotation of thesupport ring.
 4. The bearing assembly of claim 3 wherein the axis ofrotation of the support ring is substantially perpendicular to each ofthe corresponding tilt axes.
 5. The bearing assembly of claim 1 whereineach of the plurality of tilting members includes a convex tiltingfeature.
 6. The bearing assembly of claim 5 wherein the convex tiltingfeature includes at least one of a generally semi-elliptical pivot, agenerally semi-hemispherical pivot, a rounded pivot, a rocker pivot, ora generally semi-cylindrical pivot.
 7. The bearing assembly of claim 5wherein the convex tilting feature includes a generally hemispherical, arounded, or a generally cylindrical pivot.
 8. The bearing assembly ofclaim 1 wherein the each of the plurality of tilting members secures acorresponding one of the plurality of superhard bearing elements to thesupport ring.
 9. The bearing assembly of claim 1 wherein each of theplurality of superhard bearing elements is tiltable about thecorresponding tilt axis by about 0.5 degrees to about 20 degrees. 10.The bearing assembly of claim 1 wherein the base portion includes a baserecess extending at least partially therethrough and having acorresponding tilting member of the plurality of titling memberspositioned at least partially therein.
 11. The bearing assembly of claim10 wherein the base recess is a through hole.
 12. The bearing assemblyof claim 10 wherein the base recess is a blind hole.
 13. The bearingassembly of claim 1 wherein each of the plurality of tilting members isa pin.
 14. The bearing assembly of claim 1 wherein the base portionincludes a metallic portion attached to a substrate that is attached tothe superhard element.
 15. The bearing assembly of claim 1 wherein eachof the corresponding tilt axes is closer to one of a leading edge or atrailing edge thereof.
 16. The bearing assembly of claim 1 wherein eachof the corresponding tilt axes is substantially centered relative to aleading edge and a trailing edge thereof of a corresponding one of theplurality of superhard bearing elements.
 17. The bearing assembly ofclaim 1 wherein the superhard element includes a polycrystalline diamondbody having the bearing surface.
 18. The bearing assembly of claim 17wherein the polycrystalline diamond body is bonded to a substrate. 19.The bearing assembly of claim 1 wherein each of the plurality of tiltingmembers allows a corresponding one the plurality of superhard bearingelements to tilt in a single direction.
 20. The bearing assembly ofclaim 1 wherein each of the plurality of tilting members allows acorresponding one the plurality of superhard bearing elements to tilt intwo directions.
 21. The bearing assembly of claim 1 wherein: the baseportion includes a base recess extending and at least partiallytherethrough and having a corresponding tilting member of the pluralityof tilting members positioned at least partially therein; and each ofthe plurality of tilting members includes a convex tilting feature thathas a generally hemispherical, a rounded, or a generally cylindricalpivot.
 22. A bearing apparatus, comprising: a first bearing assemblyincluding: a first support ring; a plurality of superhard bearingelements positioned on the first support ring, each of the plurality ofsuperhard bearing elements including a superhard element having abearing surface and a base portion bonded to the superhard element; aplurality of tilting members, each of the plurality of tilting membersattached to or integrated with a corresponding one of the base portions,each the plurality of tilting members including an elongated portiondefining a longitudinal axis that does not intersect the bearing surfaceof a corresponding one of the plurality of superhard bearing elements,the elongated portion configured to allow a corresponding one of theplurality of superhard bearing elements to tilt about a correspondingtilt axis; and a second bearing assembly including: a second pluralityof superhard bearing elements generally opposed to the plurality ofsuperhard bearing elements of the first bearing assembly; and a secondsupport ring that carries the second plurality of superhard bearingelements.
 23. A motor assembly for use in drilling a subterraneanformation, the motor assembly comprising: a motor operable to applytorque to a rotary drill bit, the motor operably coupled to a bearingapparatus, the bearing apparatus including a rotor and a stator; andwherein at least one of the stator or the rotor includes: a supportring; a plurality of superhard bearing elements positioned on thesupport ring, each of the plurality of superhard bearing elementsincluding a superhard element having a bearing surface and a baseportion bonded to the superhard element; and a plurality of tiltingmembers, each of the plurality of tilting members attached to orintegrated with a corresponding one of the base portions, each theplurality of tilting members including an elongated portion defining alongitudinal axis that does not intersect the bearing surface of acorresponding one of the plurality of superhard bearing elements, theelongated portion configured to allow a corresponding one of theplurality of superhard bearing elements to tilt about a correspondingtilt axis.